diff --git a/html/semantics/embedded-content/the-video-element/video-loading-attr-default.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-attr-default.tentative.html
new file mode 100644
index 00000000000000..171f245527acb4
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-attr-default.tentative.html
@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<video id="target"></video>
+
+<script>
+  const video = document.getElementById("target");
+
+  test(() => {
+    assert_equals(
+      video.loading,
+      "eager",
+      "Video loading property should be 'eager' when attribute is not set"
+    );
+  }, "Video loading attribute default should be eager when not set");
+</script>
+
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-attr-lazy.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-attr-lazy.tentative.html
new file mode 100644
index 00000000000000..82c481302d1add
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-attr-lazy.tentative.html
@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<video id="target" loading="lazy"></video>
+
+<script>
+  const video = document.getElementById("target");
+
+  test(() => {
+    assert_equals(
+      video.loading,
+      "lazy",
+      "Video loading attribute should be 'lazy' when set to 'lazy'"
+    );
+  }, "Video loading attribute should reflect the loading content attribute");
+</script>
+
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-attr-reflect.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-attr-reflect.tentative.html
new file mode 100644
index 00000000000000..0e3858b6f56134
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-attr-reflect.tentative.html
@@ -0,0 +1,63 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<video id="target"></video>
+
+<script>
+  const video = document.getElementById("target");
+
+  test(() => {
+    video.removeAttribute("loading");
+    assert_equals(video.loading, "eager", "Default value should be 'eager'");
+  }, "Video loading attribute default value is 'eager'");
+
+  test(() => {
+    video.setAttribute("loading", "lazy");
+    assert_equals(video.loading, "lazy", "loading='lazy' should reflect as 'lazy'");
+  }, "Video loading attribute reflects 'lazy'");
+
+  test(() => {
+    video.setAttribute("loading", "eager");
+    assert_equals(video.loading, "eager", "loading='eager' should reflect as 'eager'");
+  }, "Video loading attribute reflects 'eager'");
+
+  test(() => {
+    video.setAttribute("loading", "invalid");
+    assert_equals(video.loading, "eager", "Invalid value should reflect as 'eager'");
+  }, "Video loading attribute with invalid value reflects as 'eager'");
+
+  test(() => {
+    video.setAttribute("loading", "");
+    assert_equals(video.loading, "eager", "Empty string should reflect as 'eager'");
+  }, "Video loading attribute with empty string reflects as 'eager'");
+
+  test(() => {
+    video.setAttribute("loading", "LAZY");
+    assert_equals(video.loading, "lazy", "Uppercase 'LAZY' should reflect as 'lazy'");
+  }, "Video loading attribute is case-insensitive for 'lazy'");
+
+  test(() => {
+    video.setAttribute("loading", "EAGER");
+    assert_equals(video.loading, "eager", "Uppercase 'EAGER' should reflect as 'eager'");
+  }, "Video loading attribute is case-insensitive for 'eager'");
+
+  test(() => {
+    video.loading = "lazy";
+    assert_equals(video.getAttribute("loading"), "lazy", "Setting IDL to 'lazy' should set content attribute");
+    assert_equals(video.loading, "lazy", "IDL should reflect 'lazy'");
+  }, "Setting video.loading IDL attribute to 'lazy'");
+
+  test(() => {
+    video.loading = "eager";
+    assert_equals(video.getAttribute("loading"), "eager", "Setting IDL to 'eager' should set content attribute");
+    assert_equals(video.loading, "eager", "IDL should reflect 'eager'");
+  }, "Setting video.loading IDL attribute to 'eager'");
+
+  test(() => {
+    video.loading = "invalid";
+    assert_equals(video.getAttribute("loading"), "invalid", "Setting IDL to 'invalid' should set content attribute");
+    assert_equals(video.loading, "eager", "IDL should reflect 'eager' for invalid content attribute");
+  }, "Setting video.loading IDL attribute to invalid value");
+</script>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-autoplay-deferred.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-autoplay-deferred.tentative.html
new file mode 100644
index 00000000000000..098e6353c03591
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-autoplay-deferred.tentative.html
@@ -0,0 +1,35 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+  #target {
+    position: absolute;
+    top: 1000vh;
+  }
+</style>
+
+<video id="target" src="/media/A4.mp4" loading="lazy" muted playsinline autoplay></video>
+
+<script>
+  const t = async_test(
+    "Video with loading=lazy and autoplay that is not visible in viewport does not load video data or autoplay"
+  );
+
+  const video = document.getElementById("target");
+
+  video.addEventListener("loadstart", () => {
+    t.step(() => {
+      assert_unreached("Video should not fire loadstart event when not visible in viewport");
+    });
+  });
+
+  t.step_timeout(() => {
+    assert_equals(video.readyState, HTMLMediaElement.HAVE_NOTHING);
+    assert_true(video.paused, "Video should not autoplay when not visible in viewport");
+    t.done();
+  }, 2000);
+</script>
+</body>
+</html>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-eager.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-eager.tentative.html
new file mode 100644
index 00000000000000..209421c7aba2c5
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-eager.tentative.html
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+  .below-viewport {
+    position: absolute;
+    top: 1000vh;
+  }
+</style>
+
+<video id="below_viewport" class="below-viewport" src="/media/A4.mp4?pipe=trickle(d2)" loading="eager"></video>
+
+<script>
+  const belowViewportVideo = document.getElementById("below_viewport");
+  let dataLoaded = false;
+
+  async_test(t => {
+    belowViewportVideo.addEventListener("loadeddata", t.step_func(() => {
+      dataLoaded = true;
+      t.done();
+    }));
+
+    //if data is not loaded after 5 seconds, assert unreached
+    t.step_timeout(() => {
+      assert_unreached("Eager video should load data immediately");
+    }, 5000);
+  }, "Videos with loading='eager' load immediately regardless of viewport position");
+</script>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-lazy-autoplay-when-visible.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-lazy-autoplay-when-visible.tentative.html
new file mode 100644
index 00000000000000..53bd8d47982a53
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-lazy-autoplay-when-visible.tentative.html
@@ -0,0 +1,47 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+  #target {
+    position: absolute;
+    top: 1000vh;
+  }
+</style>
+
+<video id="target" src="/media/A4.mp4" loading="lazy" muted playsinline autoplay width="100" height="100"></video>
+
+<script>
+  const video = document.getElementById("target");
+
+  const t = async_test(
+    "Video with loading=lazy and autoplay does not play while not visible, then plays once scrolled into view"
+  );
+  let scrolledIntoView = false;
+
+  t.step_timeout(() => {
+    // Verify video has not played before scrolling
+    t.step(() => {
+      assert_true(video.paused, "Video should be paused when not visible in viewport");
+    });
+
+    // bind to play event to assert true that play has begun after scroll has been called
+    video.addEventListener("play", () => {
+      t.step(() => {
+        assert_true(scrolledIntoView, "Video should fire play event after scrolling into view");
+      });
+      t.done();
+    });
+
+    // scroll into view and set scrolledIntoView to true
+    step_timeout(() => {
+      scrolledIntoView = true;
+      video.scrollIntoView();
+    }, 1000);
+  }, 2000);
+
+
+</script>
+</body>
+</html>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-lazy-in-viewport.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-lazy-in-viewport.tentative.html
new file mode 100644
index 00000000000000..d08b29e11ecb12
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-lazy-in-viewport.tentative.html
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<video id="target" src="/media/A4.mp4?pipe=trickle(d2)" loading="lazy"></video>
+
+<script>
+  const video = document.getElementById("target");
+
+  let windowLoadFired = false;
+
+  async_test(t => {
+    window.addEventListener("load", t.step_func(() => {
+      windowLoadFired = true;
+    }));
+
+    video.addEventListener("loadstart", t.step_func(() => {
+      assert_true(windowLoadFired, "Window load event should fire before loadstart for lazy video in viewport");
+      t.done();
+    }));
+
+  }, "In-viewport video with loading='lazy' fires window load before loadstart");
+</script>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-lazy-load-when-visible.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-lazy-load-when-visible.tentative.html
new file mode 100644
index 00000000000000..159b927fa9c36b
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-lazy-load-when-visible.tentative.html
@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+  #target {
+    position: absolute;
+    top: 1000vh;
+  }
+</style>
+
+<video id="target" controls src="/media/A4.mp4" loading="lazy"></video>
+
+<script>
+  const video = document.getElementById("target");
+
+  const t = async_test(
+    "Video with loading=lazy does not fetch video while not visible, then fetches video once scrolled into view"
+  );
+
+  // Step 1: Not visible => check initial dimensions.
+  t.step_timeout(() => {
+    t.step(() => {
+      const initialWidth = video.offsetWidth;
+      const initialHeight = video.offsetHeight;
+
+      // Step 2: Scroll into view => video should load and dimensions should change.
+      video.scrollIntoView();
+
+      t.step_timeout(() => {
+        t.step(() => {
+          const finalWidth = video.offsetWidth;
+          const finalHeight = video.offsetHeight;
+          assert_not_equals(
+            finalWidth,
+            initialWidth,
+            "Video width should change after video loads"
+          );
+          assert_not_equals(
+            finalHeight,
+            initialHeight,
+            "Video height should change after video loads"
+          );
+        });
+        t.done();
+      }, 2000);
+    });
+  }, 2000);
+</script>
+</body>
+</html>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-lazy-poster-when-visible.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-lazy-poster-when-visible.tentative.html
new file mode 100644
index 00000000000000..fc56c84c47cc1b
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-lazy-poster-when-visible.tentative.html
@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+  #target {
+    position: absolute;
+    top: 1000vh;
+  }
+</style>
+
+<video id="target" poster="/media/2048x1360-random.jpg" loading="lazy"></video>
+
+<script>
+  const video = document.getElementById("target");
+
+  const t = async_test(
+    "Video with loading=lazy does not fetch poster while not visible, then fetches poster once scrolled into view"
+  );
+
+  // Step 1: Not visible => check initial dimensions.
+  t.step_timeout(() => {
+    t.step(() => {
+      const initialWidth = video.offsetWidth;
+      const initialHeight = video.offsetHeight;
+
+      // Step 2: Scroll into view => poster should load and dimensions should change.
+      video.scrollIntoView();
+
+      t.step_timeout(() => {
+        t.step(() => {
+          const finalWidth = video.offsetWidth;
+          const finalHeight = video.offsetHeight;
+          assert_not_equals(
+            finalWidth,
+            initialWidth,
+            "Video width should change after poster loads"
+          );
+          assert_not_equals(
+            finalHeight,
+            initialHeight,
+            "Video height should change after poster loads"
+          );
+        });
+        t.done();
+      }, 2000);
+    });
+  }, 2000);
+</script>
+</body>
+</html>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-lazy-to-eager.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-lazy-to-eager.tentative.html
new file mode 100644
index 00000000000000..96fb0afadefac2
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-lazy-to-eager.tentative.html
@@ -0,0 +1,76 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+  .below-viewport {
+    position: absolute;
+    top: 1000vh;
+  }
+</style>
+
+<video id="video_lazy_to_eager" class="below-viewport" src="/media/A4.mp4" loading="lazy"></video>
+<video id="video_remove_attr" class="below-viewport" src="/media/A4.mp4?remove-attr" loading="lazy"></video>
+
+<script>
+  const video1 = document.getElementById("video_lazy_to_eager");
+  const video2 = document.getElementById("video_remove_attr");
+
+  const url1 = new URL(video1.src, location.href).href;
+  const url2 = new URL(video2.src, location.href).href;
+
+  async_test(t => {
+    // Verify videos haven't loaded yet
+    t.step_timeout(() => {
+      t.step(() => {
+        assert_equals(
+          performance.getEntriesByName(url1).length,
+          0,
+          "Video should not have loaded while lazy and outside viewport"
+        );
+      });
+
+      // Change loading to eager - should trigger load
+      video1.loading = "eager";
+
+      t.step_timeout(() => {
+        t.step(() => {
+          assert_greater_than(
+            performance.getEntriesByName(url1).length,
+            0,
+            "Video should load after setting loading='eager'"
+          );
+        });
+        t.done();
+      }, 1000);
+    }, 500);
+  }, "Below-viewport video with loading='lazy' loads when changed to loading='eager'");
+
+  async_test(t => {
+    // Verify video hasn't loaded yet
+    t.step_timeout(() => {
+      t.step(() => {
+        assert_equals(
+          performance.getEntriesByName(url2).length,
+          0,
+          "Video should not have loaded while lazy and outside viewport"
+        );
+      });
+
+      // Remove loading attribute - should put it in default eager state
+      video2.removeAttribute("loading");
+
+      t.step_timeout(() => {
+        t.step(() => {
+          assert_greater_than(
+            performance.getEntriesByName(url2).length,
+            0,
+            "Video should load after removing loading attribute"
+          );
+        });
+        t.done();
+      }, 1000);
+    }, 500);
+  }, "Below-viewport video with loading='lazy' loads when loading attribute is removed");
+</script>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-lazy-window-onload.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-lazy-window-onload.tentative.html
new file mode 100644
index 00000000000000..53dd8e169e9daa
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-lazy-window-onload.tentative.html
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<video
+  id="target"
+  src="/media/A4.mp4?pipe=trickle(d2)"
+  loading="lazy"
+></video>
+
+<script>
+  async_test(t => {
+    const video = document.getElementById("target");
+
+    window.addEventListener("load", t.step_func_done(() => {
+      assert_less_than(
+        video.readyState,
+        video.HAVE_CURRENT_DATA,
+        "Video should not have finished loading before window.onload fired"
+      );
+    }));
+  }, "Video with loading=lazy does not delay window onload event");
+</script>
+
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-load-deferred.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-load-deferred.tentative.html
new file mode 100644
index 00000000000000..2dcecf2a9e1ad6
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-load-deferred.tentative.html
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+  #target {
+    position: absolute;
+    top: 1000vh;
+  }
+</style>
+
+<video id="target" src="/media/A4.mp4" loading="lazy"></video>
+
+<script>
+  const t = async_test(
+    "Video with loading=lazy that is not visible in viewport does not load video data"
+  );
+
+  const video = document.getElementById("target");
+
+  t.step_timeout(() => {
+    t.step(() => {
+      assert_equals(video.readyState, HTMLMediaElement.HAVE_NOTHING);
+    });
+    t.done();
+  }, 1000);
+</script>
+</body>
+</html>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-load-preload-auto-deferred.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-load-preload-auto-deferred.tentative.html
new file mode 100644
index 00000000000000..8255bf87c3bfd4
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-load-preload-auto-deferred.tentative.html
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+  #target {
+    position: absolute;
+    top: 1000vh;
+  }
+</style>
+
+<video id="target" src="/media/A4.mp4" loading="lazy" preload="auto"></video>
+
+<script>
+  const t = async_test(
+    "Video with loading=lazy and preload=auto that is not visible in viewport does not load video data"
+  );
+
+  const video = document.getElementById("target");
+
+  t.step_timeout(() => {
+    t.step(() => {
+      assert_equals(video.readyState, HTMLMediaElement.HAVE_NOTHING);
+    });
+    t.done();
+  }, 1000);
+</script>
+</body>
+</html>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-load-preload-metadata-deferred.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-load-preload-metadata-deferred.tentative.html
new file mode 100644
index 00000000000000..25b0590386788c
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-load-preload-metadata-deferred.tentative.html
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+  #target {
+    position: absolute;
+    top: 1000vh;
+  }
+</style>
+
+<video id="target" src="/media/A4.mp4" loading="lazy" preload="metadata"></video>
+
+<script>
+  const t = async_test(
+    "Video with loading=lazy and preload=metadata that is not visible in viewport does not load video data"
+  );
+
+  const video = document.getElementById("target");
+
+  t.step_timeout(() => {
+    t.step(() => {
+      assert_equals(video.readyState, HTMLMediaElement.HAVE_NOTHING);
+    });
+    t.done();
+  }, 1000);
+</script>
+</body>
+</html>
diff --git a/html/semantics/embedded-content/the-video-element/video-loading-poster-deferred.tentative.html b/html/semantics/embedded-content/the-video-element/video-loading-poster-deferred.tentative.html
new file mode 100644
index 00000000000000..14e5faf05fd93f
--- /dev/null
+++ b/html/semantics/embedded-content/the-video-element/video-loading-poster-deferred.tentative.html
@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+<link rel="author" title="Squarespace" href="https://www.squarespace.com/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+  #target {
+    position: absolute;
+    top: 1000vh;
+  }
+</style>
+
+<video id="target" src="/media/A4.mp4" poster="/media/1x1-green.png" loading="lazy"></video>
+
+<script>
+  const t = async_test(
+    "Video with loading=lazy that is not visible in viewport does not load poster image"
+  );
+
+  const video = document.getElementById("target");
+  const posterUrl = new URL(video.poster, location.href).href;
+
+  t.step_timeout(() => {
+    t.step(() => {
+      const entries = performance.getEntriesByName(posterUrl);
+      assert_equals(entries.length, 0, "No network requests should be made for poster image");
+    });
+    t.done();
+  }, 1000);
+</script>
+</body>
+</html>
