Even if you've seen Martin Luther King Jr.'s "I have a dream" speech, odds are you've never seen it the way you can in The March (8 p.m., PBS/Ch. 7).Denzel Washington narrates this documentary about the 1963 March on Washington, and it's full of footage that surprised director John Akomfrah."I was surprised at the lack of material as well as the abundance," he said. "It's an odd thing to say. But a lot of the TV coverage has been lost. Quite a bit has been trashed, frankly. And it's surprises you because you think that something that, you know, iconic an event would be preserved."But they do have "the best 35 millimeter copy" of King's iconic speech."It's not all of it," Akomfrah said. "But for the first time, people will actually hear and see this man, Dr. Martin Luther King, make that speech. For me, that was invaluable."Elsewhere on TV ...Whose Line Is It Anyway? (7 p.m., CW/Ch. 30): Laila Ali is the guest.America's Got Talent (8 p.m., NBC/Ch. 5): A dozen acts perform in New York..So You Think You Can Dance (7 p.m., Fox/Ch. 13): The remaining six contestants perform; two are eliminated.Rizzoli & Isles (7 and 9 p.m. TNT): An amateur drag race turns deadly.Big Brother (8 p.m., CBS/Ch. 2): The veto competition takes place.Capture (8 p.m., CW/Ch. 30): The hunting teams panic when they don't catch anyone on the first day.Perception (8 and 10 p.m., TNT): Moretti is in trouble after taking matters into her own hands.Pretty Little Liars (9 p.m., ABC Family): A riddle leads the Liars to Ravenswood.Twisted (10 p.m., ABC Family): Lacey has to make a choice.Who Do You Think You Are? (10 p.m., TLC): Cindy Crawford learns about her family history.Covert Affairs (10 p.m., USA): Annie is teamed with a veteran operative.Suits (11 p.m., USA): Harvey and Stephen argue over Ava's case.