Quoting from the film makers site: Mellodrama, a documentary by Dianna Dilworth, explores the rising and falling fortunes of the Mellotron – the first musical keyboard to “sample” the sounds of other instruments – from its birth in a California garage in the 1950s, through its dominance on concert stages in the 1970s, through its almost religious cult of followers in the 2000s. From the Beatles’ “Strawberry Fields Forever” to Black Sabbath to Kanye West, Mellodrama is a 50-year odyssey of musical invention, revolution, betrayal, and rediscovery.

The Mellotron is a keyboard instrument that plays prerecorded tape loops. It was invented as the Chamberlin organ in Harry Chamberlin’s Southern California backyard in the late 1940s. Harry wanted to sell his “orchestra at your fingertips” to every Aunt Mable in America, and drove his motor home across America doing so. But his trusted salesman Bill Franson took two instruments to England, and found manufacturers to replicate the Chamberlin. Under this dubious pretense, the Mellotron was born.

Mellodrama chronicles the fascinating fifty-year history using interviews with Brian Wilson (Beach Boys), Mike Pinder (Moody Blues), Rod Argent (The Zombies), Rick Nielsen (Cheap Trick), Ian McDonald (King Crimson), Brian Kehew (Author “Recording the Beatles”), Jon Brion [Producer--Kanye West, Fiona Apple, Aimee Mann], Patrick Moraz (Yes), Jesse Carmichael (Maroon 5), Matthew Sweet (Recording Artist), Michael Penn (Recording Artist), Richard Chamberlin (The Chamberlin Company), David Kean (Mellotron Archives) Markus Retch (Mellotron Archives), Geoff Unwinn (Former Employee, Mellotronics Ltd), Tom Rhea (Berklee School of Music), Pea Hicks (Optiganally Yours), among many others.

thanks for the tip Tim N!