"Casting By"

Director Tom Donahue talks about his documentary “Casting By,” which spotlights filmmaking’s unsung hero—the casting director. He looks at casting pioneers like Marion Dougherty and Lynn Stalmaster, who were iconoclasts whose taste and instincts helped change the old studio system and usher in New Hollywood through landmark movies like “Midnight Cowboy,” “The Graduate,” “Butch Cassidy and the Sundance Kid” and “Bonnie and Clyde.” “Casting By” debuts August 5 at 9 pm on HBO.