GEL Conference: http://www.gelconference.com/videos/ http://www.gelconference.com/videos/ Talks by Sal Khan, the Gregory Brothers (they show off their a cappel

GEL Conference: http://www.gelconference.com/videos/ http://www.gelconference.com/videos/ Talks by Sal Khan, the Gregory Brothers (they show off their a cappella chops) and others.