If you would like some more information on the movie and what the Naudet brothers were doing when they ended up filming one of only three shots of the first plane hitting the North Tower read here.

If you have not seen it, you should definitely watch it!!!

Here is the movie – warning language/graphic:

http://www.firecritic.com/2009/09/19/911-naudet-film-in-its-entirety-online/