So...I accidentally found this on nico nico douga. It's a live footage of Hoshino-sensei drawing out a few characters on a board in Jump Festa 2011.
http://www.nicovideo.jp/watch/1293446898 *You need to be a member to login and watch
EDIT: Now you can watch it on youtube.
Part 1 →
http://www.youtube.com/watch?v=_CyHj3cB6jQ
Part 2 →
http://www.youtube.com/watch?v=mbigmYrT3Lg Kudos to
kurosaki9 for the links!