Apparently you only need the playsinline attribute…
I have a working example with just that code:
http://vincent.polenordstudio.fr/snap/3w7kq.jpg
At least on iPhone / IOS10
<video playsinline autoplay loop muted style="min-width:100%; min-height:100%;" >
<source type="video/mp4" src="//bg.cdn.ustudio.com/app/transcodes/TQAdh6DJdtuY.mp4">
<source type="video/webm" src="//bg.cdn.ustudio.com/app/transcodes/TuX1xml2yZsS.webm">
</video>
EDIT: Ok so neither theweeknd.com nor my example work on Android. So i suspect this method only works for iOS10. Maybe also on very modern Androids handsets and browsers…
EDIT2: I confirm all of the above