This is an extremely rare event.

In this case their was abundant video.

Usually no one is around when cops are being bad, and their cop cams are always flipped off?

I don't know. There is a long history of cops being "prosecuted" in court theater and being found not guilty. This is generally only in high-profile cases. It is still fairly common to simply suspend an officer or "fire" them, allowing them to get a job in another department. So common that when we investigate folks in the high-profile cases, a history of misconduct isn't a surprise.