There's this: https://github.com/jurisgalang/jquery-sexypost which is a fit for a more general use-case, but it allows you to attach to upload events and roll your own progress indicator.
Whoever applied the crank on you, wasn't being careful (especially if it was someone more experienced or higher belt) - you can always stop short of finishing the move against someone and wait for them to tap.
Totally agree on this. I've been training for 5 years. It has a very low barrier to entry (you get to spar on your first day) and nearly infinite variations on a small set of moves.
A really cool thing about it is that, unlike most martial arts, it's not attribute based (eg: boxing, were you need speed and strength and weight) that it's possible to see 125lb players going against 205lb opponents and winning (or at least surviving)
It's very pragmatic, all the mystical components have been stripped out (it's actually a disadvantage in BJJ); in my opinion, the only other martial art that could go toe-to-toe with a BJJ practitioner would be a Muay Thai fighter - but then if the fight goes to ground (which is almost a given for almost any fight) then it's over.