That's the thing. I've looked through the level data used Ch2r, but all I can find are directories ("floodjuggernaut" and "lordhood" or something like that). The directories contain nothing except for one file (it was a "bitmap", or so the program told me). No model data, no skins, no animation, nada. My only guess is that I really suck at this sort of thing (likely), or that the guy who made that video wasn't using a retail copy of Halo 2 (pretty likely, in my opinion).
I found it interesting that one of the first sections of the "Flood" level (the first level you discover the Flood, I don't remember what it's called) is called Juggernaut. I'm guessing this was where the monster was supposed to be revealed.
well MS didnt re-release the first halo with live capability...no doubt people would have rebought the same damn game for that, hell..they were still buying the first at basically full price years after it came out. but this is interesting. Its sad what became of this game...but at least the multiplayer is still good. I mean single player modes arent really what make these games anyways.