All the following videos are about passion, energy, dreams and other important things. They're around 20 minutes each and the wisdom intake definitely makes them worth watching.

Ken Robinson says schools kill creativity
Ken Robinson: Bring on the learning revolution!

Steve Jobs' Stanford commencement address [2005]
Eric Schmidt's University of Pennsylvania commencement address [2009]
Eric Schmidt's Carnegie Mellon University commencement address [2009] (has much in common with the Pennsylvania one)
Larry Page's University of Michigan commencement address [2009]
Marissa Mayer's IIT commencement address [2009]
Jeff Bezos' Princeton University commencement address [2010]

Update 25/9:
Randy Pausch Last Lecture: Achieving Your Childhood Dreams [2007] (thanks ithilgore)
Randy Pausch CMU graduate speech [2008]

-- Mahatma Gandhi