Long before A.I., Walter Murch had a love affair with a machine. It was called the Moviola, and together they embarked on an analog romance to which his wife, Aggie, eventually resigned herself. Mr. Murch, who has lived in Bolinas for decades, used the machine to edit some of the most famous movies ever made, including “The Godfather,” “American Graffiti” and “Apocalypse Now.” Now he has made a documentary about how the Moviola revolutionized the…