He's having a temper tantrum as much as his daughter was. And since he didn't know how to deal with her, he publicly embarassed her by posting that video on the internet.
The video wasnt about how to punish your children, but it was all about him and his 'problems'. Essentially it's a "I'm more badass because I shot your computer, I don't need to actually work out any problems with you."
One bullet would've been enough, but eight or nine? That reminds me of a psychopath there. Shooting someone over and over despite the fact they're already dead.
I bet you he beats the **** out of his daughter, and she just needed somewhere to vent.
TL;DR
Hurr durr i have gun n bad teen, pay attention 2 me