You can easily add a looping background video to the hero section of your pages using the tools in your Twenty Over Ten dashboard.
Log into your Twenty Over Ten account.
Upload your video to the Uploads Library
Select the video you wish to use, hover over the new file, select "Copy Link", and then close out of your Uploads Library.
Select the Page Settings option for the page that will have the background video.
Scroll down to the "Background / Divider" section and replace the Video URL with your new URL.
Be sure to save your changes and publish your site to make the update live.