What I like most about these live broadcasts is not just the sense that I'm hanging out with the world's nicest guy but the way he deals with the (wide ranging!) science questions from the live audience. As he chats away looking straight down the camera lens, people pose tweet-like questions that they've typed on their phones, which then appear on screen and he answers speaking into the camera.
His answers are always respectful of where the person is coming from (no knowledge deficit model of science communication here) and his explanations are clear and often fascinating. He's not shy of being provocative either - when asked by someone if the plans for Mars trips were fake he surprised me with his answer - "they're not fake but they're not real either - it's science fiction." Ouch.