I'm no expert on these things, but she was resisting arrest and it appears that she played a part in how she ended up on the ground with how wildly she was moving.
I mean it looked bad, but she doesn't appear to have any noteworthy injuries. A real, WWF, style body-slam would've wrecked her physically.
Lord knows I'm critical of police use of force. That event in Miami the other day was ridiculous- shooting a contrite therapist with a rifle while aiming for an autistic person sitting on the ground?! The best reasoning the cop could come up with was "I don't know?!"
The therapist may not have to work again with the settlement coming his way. Pretty much a done deal in court. But this? Arguably justified use of force.
Thank God we have cameras, witnesses, and experts. Our legal system is far from perfect, but it does help sort these things out while people are fixn' to turn everything into a politically-driven witch hunt.
/rant