OK, hang with me, I'm gonna "review" this as I watch, so it might seem a bit disjointed...I'll wrap it up. (Note that I ain't no pro, but I think my experience level will let me comment....others feel free to correct.)
NB: I'm gonna watch these without sounds, since you aren't concerned about sound...it'll just throw me off, so don't get pissed if I don't comment on the music.
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PART I: OK, I've finished Part I, it was enthralling....

At first watch, it seems your hands are too far above the keys. This is causing the lack of economy in your movement; since your hands are so high up, your fingers are forced to slam down and flop around instead of play smoothly. This also could be causing the trouble you have with finger curving. Try moving the hands down closer to the keys; this should facilitate the curving of the fingers which is needed for an "emoted" performance. Let me watch again....OK, more than your entire hand, it's more like your wrists that are too far up. Try bringing the wrists closer to the keys. Everything else looks OK so far.
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PART II: Again, a lot of flapping here. It seems that you aren't moving your wrists when you play...this is very important. Your wrists should flow somewhat ahead of where your fingers are playing (again, others correct if I'm wrong, this is what I think). Otherwise, your fingers will have to work too hard to reach the keys. It's prob. hard to do with this high speed passage; in this case, simply stretch and lower the wrists a bit.
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PART III: This looks good, can't see too much to comment on here.
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PART IV: Same as above, but enjoyed the headscratching.....wait, what in God's name is going on with that lean?

I never lean out, unless it's a particularly expressive, slow passage and I'm performing something for an audience. Leaning out creates too much tension and stretching in the arms. Definitely lean in, or straight up, but please not out.
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One big thing that I've remembered after rewatching all of this: don't play with the wrists! Don't sound with the wrists. My teacher always made this painfully clear with exaggerated imitations of my bouncing wrist syndrome (hopefully cured now). Keep the wrists steady vertically and play (really press down into the key) with the fingers. This could be causing a lot of the flapping. If you need to play really loud or stuccato, use your shoulders, not your wrists.
Hope that helps, please comment on my comments, it'll make me feel better....haha

Terry