Depends on your location. Unless there is direct contact or injury you're wasting your time calling the police. Here in New Zealand we can report a bad driver on the local police website, providing all possible information. Your jurisdiction may have something similar.
Cameras are "after the fact" information. They don't stop anything from happening. I've found that a lot happens outside the camera's view. Behind and beside are areas where bad thing happen.
Personally I've found the best answer to be avoid dying or getting injured. There's nothing like seeing the problem and avoiding it.
A good loud bellow can be cathartic too, but there's no guarantee the driver will understand or even hear it. Modern vehicles have excellent sound insulation, to the point where emergency services vehicles can be almost inaudible.
Here's an example of proactive problem avoidance - I did not get doored, and the camera lets you lot enjoy it.
The particularly bad quality U-turn just before this footage was indicative of an unskilled driver, but it was too small to see on screen. Cameras are not as selective as the human eye at perceiving details. But post injury/death they could be invaluable to prove what happened, and who was in the wrong.
