Some background and context...
The original lecture was given in September of 2007 at Carnegie Mellon University. It was part of an ongoing lecture series there where top CMU faculty members were asked to consider what matters most to them, and then deliver a hypothetical "Final Lecture", with the instructions of "What wisdom would you impart to the world if you knew it was your last chance?"
The above video is from October, 2007. Since that show aired he has had a full day of practice with the Pittsburgh Steelers, fulfilling one childhood dream. When the director heard Pausch was such a huge fan of the series, he was flown out to LA where he appears, and has a line of dialog, in the new Star Trek movie. He didn't get to be Captain Kirk, but it was close.
On May 2 of this year a PET scan showed tumors had spread to his lungs, abdomen and lymph system. Two weeks later, May 18th, he delivered the Commencement Address at CMU's graduation.
YouTube - Randy Pausch addressing the CMU 2008 graduating class
It's pretty impressive, too.
Here is the original, 79 minute lecture.
YouTube - Randy Pausch Last Lecture: Achieving Your Childhood Dreams