A more legitimate police response, and scale of escalation, would have been:
1) Give her an order to leave the area immediately.If I was standing there, and an officer, without justification, had punched my wife, girlfriend, or daughter, then I GUARANTEE to you, that you would have a much bigger situation to deal with than you did before.2) If she does not immediately comply, then grab her by the arm, say "You are under arrest", and take her away.
3) IF SHE RESISTS ARREST by attempting to break free or trying to assault the officer, THEN he can legitimately use force in order to subdue her.
Then it became clear that she taunted the police until the LT told her to come here or stand there because you are under arrest.
She says screw you and turns to flee. That is against the law. She disobeyed a lawful order and tried to flee to avoid arrest when he punched her and subdued her.
Whether that punch was over the top depends upon whether the officer thought that she was so out of control and defiant that he was going to have to wrestle with her to get the handcuffs on her. She was clearly not in a cooperative mood which when it arises gives police greater leeway in their actions. It could have been worse for her.
That is my take after watching it for the 18th time.
If that were my wife or sister or daughter I would hate to be her husband or brother or father.