unfortunately no webm?
Visit https://dl8.webmfiles.org/big-buck-bunny_trailer.webm for example and it will just play.
From: https://www.webmfiles.org/demo-files/ (where its embedded with a JavaScript player)
Also see: https://caniuse.com/?search=webm
It is not javascript player. It is plain old html video tag.
Literally only for porn—I doubt I'd ever have noticed the feature was missing, otherwise—but still.