parallax site with scrolling video background?

I would like to create a site with scrolling, auto-playing full width video, without playback controls – this seems not to be possible with inbuilt means.
Did anyone get a script to run which plays a video on desktop computers and serves a still frame on mobile devices?

Here's such a script, shared at Github – but I failed figuring out how exactly (and if at all) the manual code insertation to the page body works...

Attachment 112693

Btw if a developer is reading this: Is making a native option for scrolling bg video planned?

Check this out, this is a Xara Template > http://xaratemplates.com/vendors/xar...xt93-template/

Thank you Andy! In the meantime I got a script shared at Xara-Users to work as well, one can make the clip scrollable too.
The limitation ran into (and which likely also applies to the template you showed) is that just one video er page is allowed
(the second one in the template is the same as the first, just with an overlay colour).