<audio>
and <video>
tags without Javascript.video/webm; codecs="av1"
<video preload="auto" controls="controls" autoplay="autoplay">
<source src="https://www.elecard.com/storage/video/140626_av1_720p_850kbps.webm" type='video/webm; codecs="av1"'>
</video>
HTMLMediaElement.canPlayType('video/webm; codecs="av1"')
→ MediaSource.isTypeSupported('video/webm; codecs="av1"')
→