In his new book, “Who Knew,” former television, film and media executive Barry Diller writes of his remarkable business career, while also revealing the sexuality that he kept secret from an early age. In this web exclusive, Diller sits down with correspondent Tracy Smith to talk about why he thought revealing his sexuality would be “dangerous”; his early days at William Morris; his decades-long relationship with fashion designer Diane Von Furstenberg; and the process of writing a memoir, in which he would “pull the stitches” of memory.