The eyelid movement I am thinking of is the earlier one that is paired with hand gestures.
Source: https://youtu.be/RsQCXN4o4Ps?t=27
If you look specifically at the eye brow - there is what *looks like* micro muscular movement. Most VFX artists will confirm that the some hardest things to fake are small details of muscle moving under skin. (see: corridor crew's VFX artists react series as an example.)
This is not me saying that the "footage" is real - but that kind of detail on a CG model would have been hard in 2011. Not impossible probably, but certainly would take a significant time investment.
Also, it has been mentioned in various places, but it's worth watching all 3 videos at between 1.5 and 2.0 speed. The timecode is closer to real time and the "footage" may have been slowed down for whatever reason.
If nothing else it's another way to analyze the videos.
If I had to guess - some kind of stop motion with animatronics? I really haven't figured it out. Everytime I look for details (aside from filters) that might give a clue or expose a flaw - I cannot find any major flaws in any of the detail in the images.
Here's an example: I had originally thought maybe there was some odd artifacts in this frame, but it turns out that the shot is showing the "alien" under a stadiometer. The shadow details on the head are perfect as far as I can tell.
The shadow moves realistically with the subject. You can also see what appears to be subjects head "pulsating" for lack of a better term.
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Honestly this is among the most impressive hoax videos in existence and the dedication of the OP to never come forward is a puzzle.