Your Title image is a prime illustration for the analysis of the collapse though I don't think you're quite on the mark in your latest video. The collapse isn't distinguished by the falling of the exterior facade, rather it is the collapse of support for the second floor, i.e. the inner wythes on the first floor, from which everything else follows.
If I'm not mistaken, the original structure used brickwork to support the second floor. East/West steel beams extend to the west perimeter and are encased monolithically with the second floor slab, all of which bear on the inner wythes of the west perimeter wall. I believe there are three or four wythes, one of which is the exterior facade. The exterior facade is tightly tied to the inner wythes, not utilizing air gaps as we do today. This is noticeable on the higher levels where the original brickwork is still present but falling apart, i.e. no gap where exterior facade falls away from inner wythe.
What your Title image shows brilliantly are the failing inner wythes. To the right of the door, the layer of remedial facade (not original) has fallen away revealing the decripit inner wythes, upon which the building rests. Yes, upon which the building rests! To the left of the door, the whole section has dropped as though a layer of brick work has crushed and the window frame next to it is deflected. Further to the right, the CMU's may not be picking up any bearing weight since the original distribution was directed between the window openings.
Evidence of deterioration of west wall support for the second floor is well documented. Unfortunately, all evidence reflected in the deterioration of the exterior facade has distracted from the root cause. As the second floor dropped further and further, efforts were misguidedly spent on patching up the exterior blemishes without turning adequate attention to shoring up the structure and repairing loss of functionality of the inner wythes.
It is true that the exterior facade has suffered badly from weathering and is a big problem, but that is not the direct mechanism of collapse, nor a myriad of bulges and air gaps. Watching the exterior for first signs of collapse is merely to say, where is the collapse first reflected in the exterior layer. The collapse initiates with loss of support for the second floor, i.e. the sections illustrated in your Title slide cease to function.
In my NEST animated GIF above, you can see the section of brick to the right of the door spill out. This is critical supportive material and the dying breath of the structure.
All the best and thanks for your work.
