<audio>
and <video>
tags without Javascript.video/webm
<video preload="auto" controls="controls" autoplay="autoplay">
<source src="https://github.com/chromium/chromium/raw/master/media/test/data/bear-av1.webm" type='video/webm'>
</video>
HTMLMediaElement.canPlayType('video/webm')
→ MediaSource.isTypeSupported('video/webm')
→