Wildstorm Tour with Jim Lee
http://www.youtube.com/watch?v=6VG6kGq1mJw
I've watched this a few times over the last couple of years. It's always a trip to see the behind the scenes stuff and this is no exception.
TopCow Studio Tour with Marc Silvestri
Part 1
http://www.youtube.com/watch?v=xWZ3il52aFc
Part 2
http://www.youtube.com/watch?v=SDUn2rrRhWU&feature=relmfu