Two cops from Bloomfield, NJ's police department have been indicted, and another plead guilty after a suppressed dashcam video showed them beating a man who was facing years in prison for "resisting arrest" (the DA dropped his charges right away).
In this video recorded on a dashboard-mounted camera, Raguruban Yogarajah stops his car in the middle of the highway—then lets it roll back into following traffic. Herman Sham, the other driver, claims to have been subjected to a shakedown as the two motorists examined the damage: $500 cash, or the cops get called.
Russia appears to be ground zero for this sort of shenanigan. Violent confrontations abound, but my favorite is this driver's ostentatious display of frustration and despair at being rear-ended by such an irresponsible dri--Oh wait, you have a dashcam? I'll be going, then.
There are lots of Dashcams on Amazon, but it looks like you need to spend at least $50 to get something decent. And they all kinda look janky, if you ask me. Would a GoPro be a better bet, or do you need a specialized device for battery-life reasons?