I think a video like this comes out of an understandable impulse -- the desire to give the finger to death and suffering. That's why we have Halloween and Day of the Dead and horror movies. It's why we tell stories about psycho killers around campfires. It's why there's upbeat music at the end of New Orleans jazz funerals. We want to shrink what we fear down to size so we can tell it that it's not so tough and it can't scare us.
I still wouldn't recommend this video to anyone who lost a loved one that day, any more than I would recommend Cassetteboy's even more tasteless "Fly Me to New York," a crude 9/11-themed mashup I heard within days of the event -- but "Fly Me to New York" really did have the effect (for me at least) of shrinking the events down to the size of a sick joke.
At Flopping Aces, Curt says,
In making these "funny" videos about 9/11 they hope to show the world that we really are not in danger.
That's 180 degrees wrong. It's the exact opposite of the truth.
Incidentally, Curt, I noticed this on your site:

I was going to ask you when you and your heroes in the administration were actually going to do something to bring the guys who masterminded 9/11 to justice -- but I can see that all thhose martial feelings 9/11 stirs in you are put in the service of, well, other priorities.