What I was trying to establish, was if the windows were up or low, because Jarman said they "raised" the windows when they got there, so I was trying to see in the Bronson film clip it that can be determined or not, if the window is raised yet or not. If not, and the time of Bronson is 12:25, then that's some kind of indication they haven't arrived yet.
And the box is in the window in the Bronson film not later than 12:25, so probably by the shooter right?, only AFTER BRW left, and so it almost necessitates that the shooter would have to be hiding near on the 6th floor and probably have a LOS to BRW at the SN by about 12;24, cause he had not yet chosen which boxes to use, and he has to move the big box and stack the 2 smaller boxes and then move himself so as not be in the Bronson film