I think you guys are missing the point. Imagine that the posted video actually fingers the thieves, but only after some posted comment on the video says "Hey, I know who that is, that's Joe Bike Thief." But the police and prosecution don't find out who posted the comment and don't cal him to the stand to testify. So the defense uses that ALONE to create doubt, and the thief is not convicted.
The police didn't say you cannot post, they said you should check with them first, because if your video doesn't help the case, and might hurt it. I would be pissed off if someone's posting on the Internet let my criminal escape, and here all you have is someone who wanted the next home video put up, not working toward finding the person.