Having a bit more time with the bottom video...
Claims picture must be a cutout composite--If that's true -it is an even better job than the Backyard Pictures.
2:26 --- I believe that the mysterious leather item is a strap [perhaps a camera] that is apparently sliding off the right sleeve of the suit coat. See the wrinkles on the back of the suit on his right side?
How does the narrator know that the [McLain photo] "was taken before the limo got there" What limo? I fail to see the President's car.
For those unfamiliar with old school photography...the negatives are numbered [embedded in production of the film] in the order of their exposure.
Any ultimate conclusions remains obscure