Steve, Thanks for posting that Hughes clip. I'll look over it repeatedly to see if I can discern anything notable.
I'm with you, it was really bad luck the filming stopped when it did. Just a few more seconds and we would likely have answers to a whole slew of questions.
I had a chance to look at the Hughes film here and also the version on Max Holland's National Geographic show.
It looked like there might be motion but all I could make out was basically a blob. I could not get resolution of a person or a body position. If only we had a few more seconds of film.
On the Max Holland show, he also was trying some sniper shot modeling and positioning using a 6th floor window replication. It was filmed patchy with respect to the order of the shots but I tried to cut, order and paste the first shot, second shot and third shot positions that he was looking at. The patched together version is at the link here with the three shots added over an ~10 second duration. It starts with a rifle bang right as the first shot was fired and the sniper begins to grab the bolt action getting ready for a second shot. The second shot is ~5 seconds after the first and then the video shifts to be behind the sniper as he cocks for the third shot ~5 seconds later. The pauses in the sniper’s motion after the shots would represent the time the sniper would use to reposition the rifle and aim for the next shot. Again, this is just juxtaposing some of Holland's video snippets in order with gunfire sound for a slightly longer than 10 second shooting duration, which didn't appear that unreasonable.
https://drive.google.com/file/d/15Yrbfx0ic3IXXfAhGqiAiIotHC-G3J7s/view?usp=sharing