To add a video to the background of a section, navigate to the section's Settings Cog on the left hand side of the section.
Click on the Background Tab.
Select Video.
Then click + Add Video.
Choose a video already uploaded into the Documents and Media area or select + Add File to upload a new video.
Note: The max file size for a video is 50MB.
When finished, click Save.
Because the video background for this section will not display on mobile devices, you now need to select an image to display when a user views your page on a mobile device.
Under the Mobile section, click + Add Image.
Choose an image already uploaded into the Documents and Media area or select + Add File to upload a new image. When finished, click Save.
Your video will now appear in the background of the section.