Sorry, but I recall that criticism long before Moore and his screed. He just made it more famous.
I didn't know about Bush reading to the kids prior to Moore's film, but maybe some did.
I'm pretty confident, though, that it wasn't *common knowledge* before Moore's film. Mentioning it wouldn't have made much sense before then -- meaning the video had to be made sometime after.
But setting that aside, Osama also mentions Kerry, so it could have been made no earlier than Kerry's nomination.