The thing I'm of mixed opinion is the startling amount of publicity being given to this and the possible negative impacts it could have. Seriously, if this had been the quiet sort of thing that happens day to day, I think this would have all blown over and life would proceed apace appropriately.
For what it's worth, I think the answer to violence is always more violence. Always. Occasionally violence is the solution to other problems, but usually that's when those problems involve the existing threat of violence and you're just taking a pre-emptive strike (punching someone in the face because you feel like it is NOT pre-emptive; staging an assault on the armed forces "peacefully" occupying your country is pre-emptive, you're starting the fight but this is appropriate).
Look at the American Revolution as a good example. We had problems, so we told the British off. They sent some soldiers here to force us at gunpoint to behave. There was only ever one way out of this.
Casey could have talked his way out of the whole incident. He could have gone and told a teacher, and got the kid in trouble. Then the kid would be annoyed by his angry parents, and show up and beat the @^*& out of Casey. This would be a sub-optimal outcome.
Instead he threw the kid down. Harsh, but effective, and metered decently; I mean he didn't hospitalize the kid. The next time he comes back to start something, he'll be several feet away waving his arms and shouting. It's highly likely Casey will think this is ridiculous and take it as an obvious confirmation that they both know who's on the losing end of the next fight.
We need more of this. We need people that stand up for themselves and others. Look at the kids standing around at the beginning of that video. Why didn't they punch that dude first? They simply removed themselves from the situation, just like people here spot a rapist down an alley and leave them alone to finish their brutal sexual assault on whatever girl they have gagged (yes, this happens here; we call this "civilized").
Every person that stands up for themselves is another reminder that you can't get away with that kind of crap. The ones that just won't put up with you make you look ridiculous, so you find someone else to target so you can shift ridicule off yourself and claim some form of social leadership through mob rule. When they start punching you in the face, though, you start not wanting to play this game anymore; worse, if somebody punches you in the face for being a dick to them, they're probably going to punch you in the face again when they catch you being a dick to somebody else.
We like to throw around words like "Civilized" and "Mature" when we talk about living in a society where we "recognize the need to abstain from violent behavior and solve our problems with calm, peaceful discussion." This is similar to how early to mid teens tell college kids they're "very mature" when they're 13 and want to have sex (ask any school counselor, they'll have hundreds of these stories). Violence is a vehicle of peace: you carry a sword, but you don't use it unless you really have to, and only to the extent necessary to protect yourself and those around you. Those who see violence as a tool of coercion made to get you what you want through brute force are extremely immature.
It's sad we've separated society into rabbits and wolves; even sadder that we think it's "civilized" to try to declaw the rabbits and tell the wolves to play nice.