Is this guy on the video talking about the cracking sound? http://www.youtube.com/watch?v=Seu7O6IbATU
at around 7:11
Just to m ake sure it was normal, it was a quick contionous sound here is an example of its sound ( ill try my best lol) its sounded like kkkkkkkkkkkkk... not like something slowly snapping k-k-k-k-k-k-k-. Hope my example was ok. Can't be too careful.