I've seen that video before and I still don't see any real evidence for a conspiracy theory. The history channel actually made a program to debunk pretty much everything that they bring up. Set your TIVO for "The 9/11 Conspiracies: Fact or Fiction." One or two of their ideas COULD be plausible, but to me they're reaching pretty far to say that the government knew exactly what was going to happen, or even worse, actually planned and helped execute it. The government can't keep small secrets, so to me it's about impossible that everyone involved with such a horrible and large scale conspiracy could keep it to themselves. I should note that I tend to doubt all conspiracy theories.
Either way, it was a very tragic day that changed the course of history, and no matter how many times I watch that second plane hit that tower, I am still shocked. There's just no way to describe it. I can't imagine what the victims' families went through.