And the crucial factor to evading notice: being caucasian!

Nope, people actually notice. Just do not want to interfere.

If the guy was black, the result would be different.

You mean that they will hide the fact that they see it perfectly even better? :-)

I've lived in and around NYC for a long time now, and I'm pretty sure I know what's going on here. NYC has a bad rap, people do care whether someone is stealing a bike, and people are generally not racist here either. But if there is a white guy who doesn't look too scary and he's breaking a lock, the expectation is that most likely its his own bike. Most people will only half-notice him, if at all, and are more concerned with the everyday rushing about. There is so much activity all the time, you can't bother yourself with most things. But if the person was black, it's going to attract notice, and people will think twice. And then there are some that would rush to judgement as well -- cops are the worst in this respect. Note how that guy actually helped the supposed thief at the end of the video, that's because he thought it was his bike.