Mark writes, "If you don't understand what really crazy people sound like, watch the videos and learn. It could save your life someday, which is better than sitting around watching someone like Seung-Hui Cho and wondering if they're dangerous."

Well, this sounds a little facile to me. First of all, the Seung-Hui Cho seen in those videos is probably nothing like the non-speaking loner who was seen around the VT campus. Seems likely that the grandiosity all surfaced in those last horrifying and painful rants. But I have absolutely no background in psychology to know if that's true, just guessing.
My point is that you don't need to see these videos to know the portrait of a deeply disturbed soul.
I bring it up because I know someone who worries me and many others, yet we are at a loss as to what to do. So far he's the quiet 20-something kid, the slightly over-weight loner, who works as a security guard by night, lifts weights by day, is said to have pictures of Hitler on his bedroom walls -- and owns a perfectly legal gun collection. He lives at home with his parents, who seem oblivious -- they once joked to me about his gun collection -- and are simply not approachable for many reasons.
The small police force in the tiny community where this family lives are very close-knit and there are no secrets. Before the job as the security guard, this young guy worked as the police dispatcher. Anything any of us brings up to the police will surely get back to him and his parents, and that makes us very afraid. We worry that reporting him, even anonymously, will trigger his rage and set off the sort of attack we all fear. And, as we know, until the law is broken, the police can do nothing. Do we really want cops arresting people for "weird" behavior? Who determines what's weird? Your neighbor? It's a dilemna.

We've talked to his employer and suggested that someone keep an eye on him and make note of any changes in his behavior, but there are liability issues for them as well. We know of one incident where he lost his temper on the job (because we know the woman who he yelled at, another employee who was going out the "wrong" door) but at this point there's nothing the employer can do. Besides, how many times are work-place shootings triggered by a firing?

I am somewhat worried for my own safety and that of my family, but just as worried for the safety of others. I imagine waking up someday to terrible headlines and wondering why I didn't do more. But I ask myself over and over, what can we do? Other than one arrest for shooting out stop signs from his car, he's broken no law. He's quiet. He hasn't hurt anyone. Yet.
What would you do?