<audio>
and <video>
tags without Javascript.video/webm
<video preload="auto" controls="controls" autoplay="autoplay">
<source src="https://atelier-st-andre.net/tests/error-ff43-webm-vp9/flaque2.webm" type='video/webm'>
</video>
HTMLMediaElement.canPlayType('video/webm')
→ MediaSource.isTypeSupported('video/webm')
→