Kristen Stewart, Clea DuVall, Mary Steenburgen, Mackenzie Davis, Mary Holland, Martha Stewart, Tegan and Sara

Kelly covers Keane's "Somewhere Only We Know"; Kristen Stewart and Clea DuVall; Mary Steenburgen, Mackenzie Davis and Mary Holland ("Happiest Season"); Martha Stewart; Steve Kornacki; Tegan and Sara perform.