Well these aspects are what my profession has to deal with on a regular basis. So I had to reply to this one, it is fun for me.
Firstly the ASLJ folks made a official response that it was cabin pressure. That is the official excuse and not the one you are using. Which was easily debunked quite dramatically in the video.
Likewise you won't like this.
The purple flare is not present on every wave of the flag, it has nothing to do with what we are seeing.
Secondly a change in the depth of field will result in the change in the appearance of all sizing of elements in the field of view. A change of depth of field to account for the range of motion in the that would be required would cause all objects to shrink in size and then grow again. In particular we would see the details particularly near the base of the flag moving in proportion to the amount of pixels the flag has while in frame. There is no evidence of this. I have tracked thousand of pieces of footage, and have had to deal with changing depths of field and noise. What you are describing is simply wrong.
I have simulated this point so you can see what happens when shifting the depth of field enough to cause such an effect. This is a mere shift from 35mm to 37mm in order to make the flag enter and exit frame.
View attachment 1448
It is not a gamma flare it is severe chromatic aberration. Not nearly enough to cause such an effect that is actual constant throughout. The film is poor quality, suffering from noise that is causing things to appear to wobble.
Focus will not cause the framing to change either.
There is nothing occurring as you describe in proportion to the amount of pixels that are required to shift the flag in and out of frame.
This is what I do, it is how I make a living.
Modus absens is actually in your court sorry to say ETS, because this is definitely the medium that I do in fact know quite well. Well enough to make a living from it.