HTML5 Video WebM before MP4
<video playsinline controls>
<source src="video.webm" type='video/webm; codecs="vp9, opus"'>
<source src="video.mp4" type="video/mp4">
</video>
Video source: Sintel, the Durian Open Movie Project
<video playsinline controls>
<source src="video.webm" type='video/webm; codecs="vp9, opus"'>
<source src="video.mp4" type="video/mp4">
</video>
Video source: Sintel, the Durian Open Movie Project