Youtube video format

[benoit74]

Is there anything in browsertrix crawler which forces the use of a specific video codec (typically mp4 over webm) or is it all default/automated decisions made by the browser / user-agent / youtube player?

We realize we have many (mostly only?) mp4 videos in our zimit ZIMs while we would probably prefer to have webm, but we do not yet know if it is just "bad luck" or "bad setting somewhere".

Thanks.