A few days late on this, linkage from Blogs of war.

Emergency services radio and phone calls were taken from publicly released tapes originally recorded on 11 September 2001.
The “Melissa” speaking on the phone with an unidentified 911 operator was Melissa C. Doi. The recording of her phone call was originally released during the trial of Zacarias Moussaoui.
All footage in Crystal Morning was shot on the 11th, 12th and 30th of September 2001 by David Vogler.
The audio and video used in the film is not arranged in exact chronological order.
The video of the World Trade Center rubble that appears during the post-collapse “mayday” radio calls was not shot on the same day the calls were recorded. The radio calls occurred on 11 September 2001, while the footage was recorded on 30 September 2001. link