I'm not completely sure what's going on here, but I can't tear my eyes away

It would be hypnotic even without the metronome.

Under other circumstances, I'd happily share a link to the blog where I found this video. Unfortunately, I found that blog at a time when its owner is going through some serious heartache, and I'm sure she doesn't want a bunch of new visitors coming by right now only to witness her pain. So just spare a kind thought and/or say a prayer for her as you enjoy a video that seems to be helping her get her mojo back. It's doing a lot for my mojo, too!