"Apparently no one has any definite evidence as to the actual nationality of the executioners."

exactly. no one has any verification that the video is not a fake either. there are plenty of speculations on that citing evidence in the video itself. and the details behind the last few weeks of nick berg's life seem very hard to discover or verify either. so why does everyone have such strong opinions about something that is completely unverifiable and the stories behind it confused and at odds?
because it is a brilliant piece of propaganda that allows the consumer of such to pour out his/her predjudices and hatred with chilling self-righteousness. enough to justify the killing of innocents. we live in a dark time.