It lasts for about an hour, very clear, very nice speaker. It starts with a couple of guys giving credits, just skip them, the actual speaker comes a bit later on and his voice is clear and without reverb (since the introductory guys are difficult to hear).
http://www.youtube.com/watch?v=x22o8TUdOuw
This is a very good lecture, I highly recommend it to all who are interested in astronomy and all those who would like to see if they get interested.