Humiliation has to be one of the strongest motivators out there. If you're engaging in some particularly terrible behavior, if you're called out and put on the spot for it in a situation that matters to you, chances are you're going to remember that stinging, painful embarrassment for a long time.
I'm not saying all humiliation is good, bullies who bring up the fact you still wear a retainer or have irritable bowel syndrome in front of the entire cafeteria are probably trying to humiliate you just to be jerks.
But if someone's humiliating you, so you can humble yourself for a good reason, like stopping garbage behavior, is perhaps a good thing. Which is what this dad from Florida wanted to do when he found out his son was bullying other kids.