From what I have heard the guy was a bit of a cock at the time, I don't think they were trying to hide that.
Film was how I expected it to be, you knew before you went in you'd be staring at a guy in close up for the majority of the film, his psychological breakdown and over coming that was the point of the film.
Would have been pointless if they had him fall down the rock and just skipped to the point where he cut his arm off. Both the actor and director used the video footage as reference so I guess it is as close to the real situation as we are going to get.