Meryl Streep strikes me as one of the nicest people you'd ever want to meet. Also one of the great actresses, but her down-to-earth quality is what struck me in "Theater of War," a documentary about the Public Theater's 2006 production of Bertolt Brecht's "Mother Courage and Her Children" in Central Park. She rehearses, she works with the composer, she never raises her voice, she endures full-dress rehearsals during a heat wave. The only complaint she has is that it's not a good idea for audiences to see a performance in "process," because the work looks like "bad acting."