Order World - Illuminati
Like most conspiracy theories, I believe that this one is based on the secrecy of the group. If you fail to provide details, the public will make up their own. Its not to say that some if it isn't true, but light must be given to the fact that rumors have a tendency to get out of hand.
I have not watched the actual documentary that you are speaking of, but I am familiar with the bilderburg groups legend. There are, however, other such secret organizations which also supposedly rule the world. The Illuminati are supposed to rule the world also. They are also supposedly tied to the Free Masons. But then again, the free masons have a secrecy clause about their meetings too. So the secrecy necessarily breeds rumors and conspiracy theories.
It is very hard for me to believe, in the media age of internet and blogs, that such a group could exist with absolutely no one ever getting any type of evidence that they are making all the world decisions. Do they influence world policy? Absolutely, by the very nature of the people who attend, they are people who influence world policy already. So it seems only fitting that people who decide the fate of the world anyway would get together and discuss what is best before they make their decisions.