This kind of thing annoys me.
Yes the guard over reacted - but only from the parts of the video that were shown. The poster doesnt have to post parts that show himself in a bad light. From the clip shown you know there are parts missing.
These 4-5 teenagers WERE doing something wrong and got caught. They should be facing the consequences of doing that. The guard who was put in the situation now has the spotlight firmly on him.
So what if its gone viral. The media should take responsibilty for demonizing the guard and in a way promoting breaking the law if it makes for good youtube footage.