I'm my opinion and experience, dashcams are a waste of time.. I was driving out of a supermarket and got hit by another car, they were half way over my side of the road and knocked my wing mirror off plus caused a minor scrape up the side of my car at the time.
The driver in question kept on driving and never stopped but we had footage of the accident and his reg plate.
I went home and reported it, took the footage to police, went to court and he got away with it! They even played the footage in court and used still images of the drivers face (he had his window down so it was quite clear).
They never even gave a reason as to why he got away with it, however it probably didn't help that it took the police a few weeks to even book me in for an appointment to hand over the footage?