Aaaahhhh, I see it now.
Your video is being positioned absolutely, this won’t be included in the clearfix. So you’ll either have to position it differently or calculate its height with JS and see if it is taller or shorter than the div that it’s in and adjust accordingly.
The grey bar isn’t appearing above the About section because you’ve told it to be on the bottom with this line:
background-position: bottom, top;