everybody should watch this video
All this young woman did was ignore police orders. She used no force. They could have just arrested her, but instead they used force and pain compliance to get her to listen to them. Why? Because arresting every non-violent protester for "failure to follow a valid police order" would be a burden on the cops and the courts, so they just dish justice right out on the streets. Reminds me of that movie Judge Dredd.