Well that's just sad to hear. If I see a couple arguing I generally ignore it. Lovers quarrels are not something I would get invoked with unless a guy is beating his girl to death. But if I saw something to the effect of what I saw in the video then someone's getting a bullet.
Saw a guy jam his girlfriend's face into a steering wheel once.
At that point, I had to get involved.
I can handle yelling and screaming, but if you hit her in front of me for no reason, then yeah, that's a problem.
Now if she hit him first, I'm going to let him slap the shit out of her... She earned it then.