Theme support for video headers

Hi. I downloaded this theme because I thought I could have a video hero on my homepage. I get this error when going to Header Media in the customizer: "This theme doesn’t support video headers on this page. Navigate to the front page or another page that supports video headers." How do I fix this? The odd thing is that it works intermittently. Or it did. I haven't been able to make it work accidentally in a while. Anyway, thanks if you can help.