Those are, as you noted, audio-less WEBM files, not MP4s (though it may have automatically transcoded a video into that format). It’s essentially a more-efficient form of animated GIF, not really a video in the sense that non-technical end-users likely think of it.
I don’t think Lemmy does take MP4 files. Where have you seen that?
here
and another example that
it also does sound just fine, there was no sound actually, weird So no sound of any kind on lemmy ?Those are, as you noted, audio-less WEBM files, not MP4s (though it may have automatically transcoded a video into that format). It’s essentially a more-efficient form of animated GIF, not really a video in the sense that non-technical end-users likely think of it.