True, but embedding a gif is way easier than using a javascript thing which might not be allowed in most places.

Browsers just need to support <img src="foo.mp4" style="width:256px;"> already.

It should behave exactly like a GIF, loop by default, and be usable for emojis and everything.

There is absolutely ZERO reason we should be stuck to 256 colors for things like cat videos used as chat stickers. We have had 24-bit displays for ages.