Behind the Scenes of an Adult Movie (1984)
cast - Dorothy LeMay , Jessie St. James , Desiree Cousteau , Georgina Spelvin, Merle Michaels , Samantha Fox , Brooke West , Ron Jeremy , Veronica Hart ....
The opening scene is from one of the very greatest porn movies of all time, IMHO, "The Other Side of Julie." Truly amazing film doesn't begin to describe it. And this is only ONE scene of many incredible sequences.