The Gresham College website has been revamped, and I think it looks really good... much easier to find past lectures.
Astronomy lectures are listed here: http://www.gresham.ac.uk/watch/?subject=science&subcat=astronomy . All of these lectures have transcripts, and most have audio and videos as well.
A superb resource... and not just for astronomy... the full lecture list is here: http://www.gresham.ac.uk/watch/
Yes, the website is much better and aesthetically pleasing. I really enjoy these quality lectures.