I stumbled upon this fantastic series of "Royal Institute Christmas Lectures for Children" presented by Richard Dawkins from 1991. They were first started by Michael Faraday in 1825, who I just read a bit about in a book recently so it was rather exciting that I knew who he was!
http://www.youtube.com/watch?v=jHoxZ...eature=channel
This is the first part "Waking Up in the Universe" and even though they are lectures for children I still found them extremely interesting and I really enjoy listening to Dawkins speak, he is amazingly intelligent. If you enjoy Richard Dawkins as much as I do I'd suggest checking out the Richard Dawkins and Lawrence Krauss public discussion at Stanford University, the focus of the discussion being about science education. Two brilliant men in the same room, what can I say, I was gushing just watching this!

http://www.youtube.com/watch?v=ZLctxRf7duU