Alchem Pro Video Banner.

I apologize if this is the wrong place to ask this but here′s the situation:

I have the Alchem Pro theme activated in my WP site and been trying without success to set the home banner into a full screen video the way you do so easily when using the Onetone theme.
The Alchem Pro product description says: “In the shortcode section, you could set a video background for the section, just like a banner. The video source could use MP4 video url, OGV video url and WEBM video url. You also could set the video whether mute or not and whether loop or not.”

https://www.mageewp.com/demo/?theme=alchem-pro

How can I achieve this?

Thanks much.