Question | Possible to have subs_filter match a stored var regex named sub pattern

[C0nw0nk]

So I am re-writing links like so

set $querystring "?md5=";
subs_filter (.*\.mp4) $1$querystring gir;

Replace link.mp4 file on html output

<video width="320" height="240" controls>
<source src="1.mp4" type="video/mp4">
Your browser does not support the video tag.
</video>

is it possible to take the string that the regex matched in $1 and store it like this. (The code bellow does not work) what is why I am curious if there is any other way even with Nginx Lua ?
set $storedvar $1;

Thanks in advanced fantastic module <3

[C0nw0nk]

I just tried the following same empty output and this should work since its a regex named sub pattern

set $querystring "?md5="; #query string on end of url to add
set $insertvar ""; #nginx would say unknown var unless this is here
subs_filter \"(?<insertvar>.*)\.mp4\" \"$insertvar.mp4$querystring\" gir;