It's not only OK to record people committing offences, it's an obligation in a modern society where all citizens should be encouraged to take an interest in the safety of their communities (without issuing summary judgments or punishments, of course). We do not deserve to be constantly "monitored" but once you break the laws and rules of a community, you waive a little of your liberty.

People who dig their heads in the sand and ignore minor crime while "leaving to the police" are screwing over their communities with their indifference. And teenagers? That's especially when people should get involved - kids who never learn what the boundaries are become shitty adults.