Hello Andreas,

I see that WPBakery is hiding the video on mobile this is one of their styles for the video background

@media (max-width: 767px){
     .vc_hidden-xs {
          display: none!important;
     }

}

so try adding

@media (max-width: 767px){
     .vc_hidden-xs {
          display: block!important;
     }

}

in customizer -> additional CSS

Hi Andreas,

Can you send us wp admin access in a private comment so we can have a look?

Also, we have just released version 1.5 with a fix for this issue. Plz redownload the theme from envato and do upgrade. Hard refresh the page (Ctrl+F5) when testing. 

You can remove the theme in the WP dashboard and install the new version. The content and options are not erased between upgrades.

Backup your theme before to be on the safe side.

If you did custom work and modified the theme files, you have the merge the changes.