Never mind, got it!
I was adding a column, not a section.
I don’t have that option in the background tab on my screen. I only have Image, Parralax image and video. “parallax video” is missing.
It seems to be broken in your demo too.
https://jevelin.shufflehound.com/elements/parallax-video/
Have you removed parallax video from the theme? We bought it based on the claim that it was supported, it’s key to our site design that we have a parallax video background.