Bill Nye's lectures are just as awesome live. He's a Cornell alum so he occasionally visits campus and is a good enough sport to come talk to our Astro 10x classes. Bit of a pain if you're teaching, because you'll have to shift things around in the lectures to make sure everything still gets covered, but it does boost enthusiasm.

(Last time he got one of the Cornell choirs to sing a song about Venus* to the tune of the school song.)

* I don't remember all the words, but the chorus ended with 'Venus is like Hell'.