The whole thing is still fishy. Why did he interview Nick Berg? Presumably because his leftist father suggested it. My reading of Nick Berg is that he was confused and conflicted. Moore cut the footage not from respect but because he didn't get what he was after, some sort of violent condemnation of Bush by a young guy whom he expected to be a Peace Corps leftist who could be portrayed as selflessly helping the poor, persecuted Muslim Iraqis.
As for why he showed the footage to the family, I think the answer is more publicity. Here we are with yet more publicity in the news media about this sleazy film. He could have sent them a private copy; instead he made a public show of it.
Free advertising. Moore is an expert at getting face time with the media.
Months later, he still had said footage that was not used and that supposedly was not in step with his leftist anti-American, anti-Bush views??
We will. Someday.