20/20 and DatelineNBC have both done reports on Carnival games in the past. 20/20 did one on ride safety about 15-20 years ago as well and I think Dateline did one on ride safety about 5 years ago.
There have not been any documentaries or the like produced that I am aware of, but I have always thought there is a story there. The carnival is a strong part of "Americana". There's a lot of stories there....and I think there are quite a few people that would find it interesting.
I always thought a documentary along the lines of "Baseball" or "The Civil War" detailing the history of the carnival and taking it up to its present day. I know the Carnival Train video and the Gibtown video do some of that, but there's so much more.