<audio>
and <video>
tags without Javascript.video/webm; codecs="vp9,opus"
<video preload="auto" controls="controls" autoplay="autoplay">
<source src="https://upload.wikimedia.org/wikipedia/commons/transcoded/3/36/Cosmos_Laundromat_-_First_Cycle_-_Official_Blender_Foundation_release.webm/Cosmos_Laundromat_-_First_Cycle_-_Official_Blender_Foundation_release.webm.720p.webm" type='video/webm; codecs="vp9,opus"'>
</video>
HTMLMediaElement.canPlayType('video/webm; codecs="vp9,opus"')
→ MediaSource.isTypeSupported('video/webm; codecs="vp9,opus"')
→