I'm a motorcyclist as well, and I've often wondered about trying to pitch a vigilante hardware product to our police force. I'd build a product around a button that when pressed marks the previous 15s plus the next 15s of helmet-cam footage as a candidate, then uploads that somewhere when the camera is next being charged. If the police would accept a clear camera recording of a numberplate plus a person using their phone, they could make back the cost of supplying the hardware to any motorcyclist who offers to be a vigilante in a matter of days.