Ladyjanegreysketle-I don't really care, to be honest. It was almost 23 years ago. Also, the Palestinians get bombed with American weapons all the time. Noone can expect them to be happy with the US. Nor can you expect them to ever be happy with Israel, who does the actual bombing and a lot of other unpleasant stuff. I don't blame the Palestinians for some of celebrating when they had so much suffering inflicted on them.
It's funny though, but with the sound off (I am too lazy to put on my headphones right now), and without any commentary, they could have been celebrating anything. All I see is a bunch of people waving the Palestinian flags and giving peace signs. I wouldn't know if they're celebrating September 11 without someone telling me so. As I said, Israel celebrates Palestinian suffering ALL the time. Look at the Wedding of Hate, for example. And it's obvious that they're celebrating something sinister there.