Simon.....There are a few other coincidences.....
(1) The chair that Nick Berg was sitting in appears to be the same type used in Abu Ghraib.
Of course, we don't know how common chairs like that are in Iraq. So that may not amount to anything.
(2) At the end of the videotape (after Berg died), you can distinctly hear an American-sounding voice speaking what sounds like English, and it sounds somewhat like "Thy will be done" but because of the poor sound quality, this also is far from clear. The sound file is here:
http://www.BreakForNews.com/berg-thywillbedone.mp3
Also the video has clearly been edited from two different cameras (note the different time stamps), and Berg appears to have already died by the time of the decapitation because of the lack of bursting vessels and arteries.