In the very beginning of the video, some guy on the left side of the screen slings a cup’s worth of beer at the cops, then the cop turns around, sees her holding a beer, and decks her.
Nobody here cares about context, it seems.
Yes, this seems to be an extreme overreaction by the cop. But what is the context? Maybe someone threw a beer on him, and he *thought* this woman was the person who did it. Not an excuse to punch her, of course, but maybe the trigger that set him off.