Watching that, the main thought that struck me was "thank goodness she had support".
Because it could have been much worse, and she could have been seriously hurt.
Red shorted student pulled the attacker off, and stopped the attacker going in a second time. He was able to do so effectively, and using a proportionate amount of force.
Other students pick the girl up and help her.
Sadly, I can imagine that in certain schools in certain countries this may not play out in the same way.
Even with adults, when I think of a couple of "TWAW" beardy blokes I know, they would not step in so quickly to help a woman being beaten in this way. They identify as feminists (natch) but I think would be reluctant to intervene... because they wouldn't want to physically restrain a woman, and "twaw".