Where I live. It looked like she was charging at him or a member of his family.
From what I saw in thr video, he reacted. Split second and didn't think before reacting.
Not saying an adult man knocking out a teenager (what's a 12 year old girl running with a bunch of thugs anyway...nevermind.) is right, but when you've got someone coming at you like that, you react.
I only saw the video posted here:

[link to wlos.com (secure)]

I will watch the one you posted. Of course they posted it on Worldstar. smh.