She kept yelling “Get Back” as if she was being bum-rushed. The cop to her left was day-dreaming about what kind of food he was getting for dinner.
In the video it looks like the crowd is breaking up and people are just gradually walking away. None of the other cops seem particularly bothered.
Maybe she was all cranked up on too much strong coffee. She certainly is reacting to something.
Fox News just said they have before and after footage coming up. Maybe that will explain it.