Keith Senkowski (of Bob Goat Games - Conspiracy of Shadows) has made some videos of various seminars at Gencon and posted them up on google video. I've been watching these ones in which Ron Edwards and Vincent Baker discuss DIY game design. Really good stuff there.
Warning: it's seven 8-minute chunks.
There are apparently more there, with various other people, but I will get through the other four and a half of these before checking them out.
Later edit: so now I find that there is this page here with links to all of them and also what is still on the way.