How did this knuckle-dragging, fat-ass Neanderthal get a hold of it?
The most plausible answer would be that the film had to come directly from the person taking the footage which would have to be a "fellow sympathizer." Knowing that Moore is on the same page with the terrorists, who better to send it to then a film producer in the US who they know they can trust. OR, the entire, unedited footage was given to the Berg family by the FBI and they have chosen to give maybe even sell it to Moore.