2 still frames from a video show the genral locations of the earliest visible ejections:
Slow-motion video of the earliest ejections shown backwards. Backward
motion allows the viewer to locate the earliest ejections relative to
the large perimeter panels that are ejected from the building and seen
to go into free-fall.
Note the earliest ejections on both the left and right sides of the west wall.
Ejections below the 75-77th fl MER panels
The red and blue lines mark the base of the beam flooring of the 75th fl mechanical equipment room (MER).
The 2 large corner MER perimeter sheets connected to this flooring is
ejected from the building with considerable force during the next series
of images.
The MER corner piece marked by the green line will go into free-fall down the NW coner of the building, spinning as it falls.
In the next photo the NW corner is being ejected from the building.
The first sign of a large MER perimeter sheet emerges from the dust (red circle).
The white arrow marks a light colored ejection. The evolution of the
light colored ejection allows the viewer to determine how images during
these moments are sequenced.