It would seem that the beheading of Nick Berg has become the subject of much suspicion. If you do a Google search on the subject, you can find endless theories and accusations. The video has become a Zapruder-like beacon for conspiracy buffs. Here is an article on 50 inconsistencies in the video. Of course, one needs to view the video in question to make any sense of these theories, and that isn't something I intend to do; so I will let others dwell on the suppositions. Here is an article that claims the beheading was most likely carried out on an already deceased Berg.
When I first posted about the unfortunate demise of Berg, I couldn't understand why the terrorists would make such a moronic move to dull the growing outrage regarding the prisoner abuse. I realize that revenge for said abuses was the claim for the action, but it still seemed like a counter-productive move.
There are so many questions surrounding the video and Berg himself that the conspiracy theories will continue; I doubt the truth will ever be known.