Inspired by Your demo, I took a something similar video for background in section 1 (Banner), but used it in html5 for responding in mobils too.
So I uploaded it in mp4, ogv and webm and placed the correct urls in the options form.
But it does not work all over: On desktop only in firefox, internet explorer and opera, but not e.g. in google chrome.
On mobile (android) it works also fine in firefox, but not in my other browsers.
In the console of google chrome it shows 2 errors:
– Uncaught (in promise) DOMException: The play() request was interrupted by a new load request. (video.js:91)
– Uncaught (in promise) DOMException: Failed to load because no supported source was found.
Please have a look at http://www.fresh-and-pure.de/wordpress and tell me what to do.
The video you upload http://www.fresh-and-pure.de/wordpress/wp-content/uploads/2017/06/Milky_Way_3.mp4 has errors so it can’t display in browsers which only support mp4 format. You could change to another video to check.