I watch a few, but I'm really picky about artists I like. If I'm not a total fan I'm not too interested.
Most of the artists I follow are animators, but they do have process videos.
hotdiggedydemon
Isobel Kelly
Vivziepop
makebabi.es
Pikapetey Animations
Will Terrell (I love this guys commentary)
Sorry if you weren't asking for a link spam.
I made process videos/speedpaints in my late years of high school, mainly to test out the idea but haven't done it in yeeears. I've thought about getting into it again with my comic pages, or general illustrations, but I don't have a very good setup for a webcam, and I really don't have the time to sit and do the drawing process straight through. Also, to be honest, I don't even know if readers would be interested at this point? I've tried before and didn't get much response, so I don't see much point putting in the time and effort.
Maybe someday.