This works great at YouTube EXCEPT if I try to download music videos. I hope it gets fixed soon, as it was and would be a five-star extension!

ADDED: I had paid for the Pro version, and find that if I select MP4 720p HD, it works just fine.

ADDED 7/14/21: It's fixed now, so I can download music video 360p .mp4s.

Thanks, Dishita!