http://www.terrorize.dk/911/wtc2hit13/
original source http://thewebfairy.com/911/cameraplanet/north_tower_on_fire.mov
Slideshow of frames for study: http://thewebfairy.com/911/slideshow/eh Sourcefiles: http://thewebfairy.com/911/slideshow/eh/bmp
It reminds me of a chemtrail plane, actually.....