Background video glitch

Hi,
I’m trying to add a background video to a page using these instructions:
https://docs.generatepress.com/article/adding-a-background-video/.

I was able to get it to work, but then changed something so it’s now no longer working (link below; it’s the second block on the page. You can see the video playing and in the code you can see the container block for overlaying content, but it’s not showing up on the page). Is there something obvious that I missed? Sorry for the hassle – I’ve tried to replicate this a few times and it’s still not working so I’m not sure what I’m doing wrong.

Thanks!
Elisabeth