An escalator,hard not to stop watching.
Quote:

This is a video of hundreds of Chuck E. Cheese ball pit balls perpetually falling down an escalator. They ride up, and, after failing to exit the escalator like a frightened child at the top, start bouncing back down. Plus cause a least a few people to use the stairs instead. 'Kids pee in those ball pits and these are new brand new sneakers,' I imagine those guys telling themselves.