I did try to rationalize that MIG21 video in the past. Like other people, I noticed that the ejection seat was either from an F-15 (two seater) or from a Mitsubishi F-2B, because of it's reinforced canopy with a bow frame* (unlike the F-16). Other aircrafts using the same ejection seat were not good candidates from what I remember.
I also remember that reflections were not a good candidate.
* : required for low-level flight capabilities and the attendant increased risk of bird strikes
I'm just happy to see that you found the original video. One thing that looked odd if you ask me, is that the cameraman (hand-held) did not try at all
to keep the "tube" in the center of the FOV. Some would say that g-force might explain this, since the plane was making a steep turn on the right, which would increase g-forces and make it harder for the cameraman to compensate. But hey, if the camera was kept up close to his body with his arms & elbows close to his upper body, he would not have to compensate much. That is exactly what I would have done to keep track of it and I am only a private pilote but I remember taking some pics when we were doing 3 g turns. (pushing the DR400 to the limit)
What a bunch of liars we got there !