Tom Ruprecht (Late Show with David Letterman) drops by to watch the 1970s action show, "S.W.A.T." Tom talks about how cops ain't what they used to be, discusses how posters were cool in the 1970s, and dishes on J.D. Salinger's TV obsessions and his new kindle book "This Would Drive Him Crazy: A Phony Oral History of J.D. Salinger."