As an ex police officer, I can tell you for certain that they do not often get cooperation from the public.
A lot of these guys with cameras claim it is in case they are in an accident and I can accept that. But clips like this and dozens of clips on Youtube clearly show them riding around trying to advise other motorists about the error of their ways. They would be better off taking care of their own riding.
A good example is this clip. The rider claims he saw the bus driver using the phone but then has no hesitation in riding up the Inside of him. If I thought the bus driver was driving without care, its not a move I would try.
I am not getting into a debate about this but cyclists dont have any authority to instruct other people how to behave on the road. Its how they get punched or run over or worse.
Steve