I love replies like this. Yeah. Wonderful. It's a perfect world, and I'm going to use the exactly equal amount of force to subdue her while she rakes my arms and face bloody with her claws. Because that's the morally right thing to do. Or not. I'm supposed to turn and walk away - while she continues to attack me. You really do live in la-la land don't you? Parent's basement perhaps? Never been around an enraged small animal and seen the damage they can do very very quickly?
You know why a mouse doesn't attack a cat? So why do certain women think they can abuse men and not be the target of a quick and violent reaction? Because they've been conditioned to expect the man to stand there and take it. But the fact is that men don't have a responsiblity (moral or otherwise) to allow this type of abuse. No one does. They have the authority to protect themselves. He took her to the ground so he could restrain her. She stopped. Situation deescalated. Applause for him. And fuck the social justice warriors like you.
Abuse is a word that's usually used for someone who is in an superior and difficult to challenge position to is doing something unpleasant to someone who is within their power (it might also be seen as an abuse of that power). It seems to me that you're wanting to use metaphors and terms in ways that suit you but not reality. In stereotypical roles, a mouse that attacks a cat is not, by the common use of the word, "abusing" it. However, A cat however that plays with a half-dead rodent is definitely abusing it.
To give another hypothetical example, a man who has been the victim of long-term bullying of both a physical and mental nature by his domineering wife then attacks her is not "abusing" her. She however has abused him.
In the example of that video, the guy is clearly more physically capable than the woman is, and doesn't hesitate to use that power, so saying she abused him doesn't really make any sense in the normal use of the word. Using only the content of the video as reference, it looks to me like he was provoked, and it was silly of her to lash out like that, but don't start using animal metaphors in the case of human beings because we have intelligence and nor could either person be honestly feeling that they're fighting for their life.
IMHO he used excessive force, especially as it seems that she lost consciousness, probably the result of her head hitting the pavement. All it needed was for her head or neck to come down on a hard or sharp edge and his actions could have killed or disabled her permanently, all over an argument seemingly, for which (the injury) IMO he would be found guilty of causing. It is not his duty to punish her for assaulting him.
In his position I would have just tried to keep pushing her away (though even that carries the risk of something worse happening), but that would be undeniable self-defence (unless it was obvious to me that I'm pushing her into traffic or off a bridge). The other person would either try to up their game which then entitles me to do the same in self-defence, or they back off.