[AvengingGibbons]

There's a law of physics to do with Pendulums, relating the Time Period of one cycle to the length of the rope. The swinging rocks don't swing realisticly, they swing too slowly (aka, their Time Period is too long) But you don't want to speed them up because it would alter the difficulty of that puzzle. The only way to make them look like theyre swinging more realisticly is to lengthen the rope.

Edit: Hmm, but then they'd be swinging towards the camera so far that they'd end up behind the camera (unless you had the camera moved further away from the scene, but I wouldn't wanna do that)... Oh well.. I don't know then... You could have them swinging less, but then that takes away the ferocity of the swinging boulders.

Edit2: I've just rewatched the footage, and realised I'm being far too picky. They are moving very slightly too slowly, but wouldn't worry about it too much. I do believe a slight speed increase would suprisingly increase the realism though.