This does seem a little excessive, especially after watching the dash cam video. He says she is resisting, and she says she's not, she just doesn't want her kid to see her [garbled, I assume saying being arrested or something like that], just before he throws her to the ground. But according to witness, she was trying to pull her arms away from him repeatedly (and he says the same thing in the dash cam). Her being fall down drunk probably didn't help with the fall.
Still, I'm not really shedding any tears for her.