Richard Bauckham presents this lecture in 2007 at Westminster Seminary entitled: The Four Gospels and the Other Gospels: Is Our Canon Right? Bauckham was also a guest on a couple of Unbelievable? radio programs, which can be found on this list. Check out his recent book Jesus and the Eyewitnesses: The Gospels as Eyewitness Testimony as well as his other books here.
Full MP3 Audio here. (48 min)