Here is a funny British documentary that covers 10 conspiracy theories. 9/11 isn't one of them. It presents some good evidence and arguments for conspiracies, but the narrator also seems to laugh at them at the same time too, in a light hearted way though, not a condescending way. But he does explain why people don't trust their government with good reason, and how the turning point started with the JFK assassination.
This was made in 2003 it seems, so the 9/11 conspiracy theories weren't as popular yet, or perhaps it was too sensitive of an issue at that time to be featured.