I watched Tips from the Top Floor, when I had the facilities. Felt it was a bit lightweight in content sometimes, and the presenter would ramble on about housekeeping and self-promotion stuff. But it was watchable and mostly entertaining. Haven't watched in about 3 months though.
They've several excellent ones available on itunes--free. There are about thirty there.
Hard to recommend just one, they've all got something to offer, some are audio, some video, some beginners, some very sophisticated. Download a few and then subscribe to what you like.
Others include Jeff Curto's History of Photography, recordings of his lectures for a college course on the topic and Lightsource, dedicated to lighting techniques, equipment and interviews with photographers who use creative lighting techniques.
Per the comment from J-Bravo, all of these, and many more are available on iTunes.
