I am sympathetic to the mistake, and the arrestee definitely put her in a bad position in which she could make that mistake. I have little sympathy for anyone who would resist arrest. The time to challenge an unjust arrest is after it occurred, not during the arrest. People should know that. And I have a strong feeling, correct or not, that people who don't behave properly in those scenarios kind of get what they deserve.
And yet, I definitely think that our police use excessive force, and we need to figure out a way to back that down. Today's police are trained like the military in many respects: Do what it takes to get home safe. But, the police aren't facing an enemy military, they are facing US citizens, and the standard should be higher for them before force is used. I don't think this was a good test case for handling that issue. Seems like we (the media, the nation) seem to pick all the wrong test cases for this...and even when we do pick a good test case, we end up racializing it and politicizing it, which distracts from what we need our police to do, which is stop using excessive force regardless of race.