As with most videos, this video starts after the confrontation has already begun and we can’t see what precipitated it.
But based on all the squirming and fighting back she was doing on the ground it’s clear she’s not cooperating. Surest way to get your ass beat by the cops is to fight back when they are trying to arrest you.
If the cops are trying to cuff you you just need to comply. If they did something wrong in arresting you in the first place then let the legal system sort it out.