Now, come on, folks. Let's be reasonable about this. (I know the word "reasonable" is oft misused, but give me a chance here.)
There is absolutely NOTHING wrong with being "sickened" by such a video. I haven't seen it, so obviously I didn't hear the commentary, and so I'll limit myself to commenting only on the issues that have been raised here.
It doesn't matter if you think that the tape looks like kids goofing around. It doesn't matter if none of the practices on the tape, outside the context of the Columbine shootings, are objectionable in and of themselves. When you're watching the perpetrators of one of the worst massacres of children in recent history practicing their marksmanship while making comments about killing people, that SHOULD be chilling. It's not the practices, necessarily, it's the PEOPLE in that video.
If we had video of one of the Sept. 11th hijackers practicing knife techniques at a Florida martial-arts school, would you find it "sickening" to watch? If so, does that mean you have an irrational fear of knives, or that what those men did sickens you?