But people on chatroulette are broadcast to the whole world, just one person at a time.

I know that sounds cheeky, but chatroulette users are already taking chances with privacy, they're letting some random stranger view into their lives. Maybe they're not expecting a record of their interaction to be made, but even that isn't that good of an expectation considering chatroulette videos started showing up on YouTube almost as soon as chatroulette started.