I didn't see how it was riding up and down. The idea of posting a video for opinions etc is a great one though - I'll keep that one in mind.
It sounded good and the belt looked fine to me, but don't count on my opinion for much. I always tell my wife "if something happens to you my next wife is going to be a diesel mechanic."
Twenty years from now you will be more disappointed by the things y%^&*.....oh never mind. 90% of the people on sailing forums already use that as their signature! I'm not a conformist.