Greetings, all. I'll be the first to admit I don't know much of anything about hex hacking, so if any of this is redundant or just doesn't make sense, feel free to yell at me and I'll stay on the sidelines. I figured I might as well post the results of a bit of tinkering, just in case it's actually helpful to someone.
utunnels, looks to me like those eight bytes likely define the movable joints, but I don't think it's 32 bits rotatable and 32 bits movable. It seems to me like the whole eight bytes simply define the joints which animate at all. For example, if you change those bytes in Serge's idle animation to 0000000015150000, you end up with a Serge whose upper body is paralyzed and whose legs sort of dangle and twitch around a lot. I would guess that this is the result of the upper body's animations being applied to the lower body's joints.
As an experiment, I restored the eight bytes of unknown data to their original values and decided to try zeroing out the first 0x3E bytes of each frame of the idle animation after the first. (This is a bit more than half because 0x30 leaves one of his arms animating, but don't ask me where I got that exact number, because it made sense at the time and I don't really remember why I chose it.) What happens then is that for most of the frames of his idle animation, Serge's upper body stops moving, but his legs seem to be operating pretty much as they should. Now, change the unknown bytes to 5665600000000000 (Zeroing out the 0x1515, basically.) and (with the exception of the first frame) Serge will stop moving entirely.
My guess is that those last four bytes identify which joints in the lower body to apply the last part of the animation to. If that's the case, the first part of each frame of the animation is applied to the upper body (but doesn't move it because I zeroed those parts of the frames out) and it simply discards the last part of each frame because it has no joints to apply it to. Then again, I really don't know what I'm doing, so I could be entirely on the wrong track.
