Those finishing machines are pretty cool. Turns out a lot of places use them for finishing various products...you can see them at work full of ball bearings in several How It's Made episodes, and I think some of my Modern Marvels ones show them too.
Not to get too off topic, but I've always wondered this. You can see the thousands of bearings sitting their vibrating and churning, nothing too intense, but obviously over time it's enough to polish tough metal pieces. So, what would it do to say your hand if you reached in?
I mean, on the one hand (har har) it seems like nothing at all, you'd just feel the bearings moving around. On the other hand, your flesh is obviously many times less tough than the metal pieces...so would the things just eventually start rubbing your hand raw or what? Seems paradoxical (then again, I'm not sure how long pieces are typically left in there)