Monty Python's Flying Circus (6 and 6:40 p.m.; 9 and 9:40 p.m.; 11 and 11:40 p.m., BBC America): The 45 episodes of this classic 1969-74 comedy have been remastered and begin airing (in order) on Fridays, beginning with the first two installments.

NBA playoffs (6:30 p.m., ESPN): Celtics at Pistons

National Spelling Bee (7 p.m., Ch. 4): The final rounds. (Tape-delayed)

Doctor Who (7 and 9 p.m., Sci Fi): The Sontarans begin to choke the Earth.

Dateline (8 p.m., Ch. 5): Women try to hire hitmen.

Battlestar Galactica (8 and 10 p.m., Sci Fi): The president is abducted, and a power struggle breaks out.