I spent quite a lot of time trying to figure out why video embedded like here:
<video height="256" loop autoplay muted controls id="vid"> <source type="video/mp4" src="video_file.mp4"></source> <source type="video/ogg" src="video_file.ogg"></source> </video>
starts playing automatically once the page is loaded in FireFox but cannot do autoplay in Webkit based browsers. This only happened on some random pages. So far I was unable to find the cause. I suspect some unclosed tags or extensive JS created by CMS editors.
The best fix I could get was adding this code just after the
<script> document.getElementById('vid').play(); </script>
…not pretty but somehow works.
Recently many browsers can only autoplay the videos with sound off, so you’ll need to add
muted attribute to the video tag too
<video autoplay muted> ... </video>