One of the most successful directors of epic features began as a child besotted with filming toy train wrecks with an 8mm camera. But Steven Spielberg’s latest movie, “The Fabelmans,” is a semi-autobiographical drama about his parents, and touches on a family secret he had buried for years. He talks with “60 Minutes” correspondent Lesley Stahl about the film’s recreations of the happy origins of his career, and the unhappy ending of his parents’ marriage.