NEW YORK—If you study Method acting at one of the great New York studios that grew out of the Stanislavsky system, the first thing they teach you is that acting is not about speaking, it’s about reacting. “Always watch the actor who is not speaking,” the great Freddie Kareman used to tell his classes at Carnegie Hall. “If he’s engaged and focused and concentrated, that’s when you’ll see his craft.” Or as Martin Scorsese once told me, “Pay no attention to the words. We’ll change the words. We’re looking for what’s underneath the words.” The great thing about watching a...