Are there any good "behind the scenes" films about how an audult film is made? Something like a documentary on how the actors rehearse, etc, etc...

There was a British TV multipart documentary called "Naked Hollywood", which may be available on video.  Also there was a movie specifically about Stacey Valentine called "The Girl Next Door" that followed her around with a camera and captured the "life of a pornstar".  In fact, one scene showed her coming back from a "private show" with a fan and throwing a ton of money on the bed and laughing.  Check with a video store that specializes in obscure movies... it was out in theaters, mostly small art house types, about a year and a half ago... I don't know if it's available on video, but it's a fun (and informative" movie.

We don't rehearse we just go at it, that's why were porn stars because we're already freaks and not afraid to show it.