Is your feature request related to a problem? Please describe.
When users send a photo and a video, you can only distinguish then by the file name. That is not optimal, as some users don't specifically look for the file format to see, whether someone sent just a photo, or a video that can be opened by clicking on the preview.

Describe the solution you'd like
Slap a play icon over the video preview.

Describe alternatives you've considered
None

Additional context
It does it in the web, so why not here.