Online high quality colloquium talks In my department we're thinking about showing online lectures one day per week at lunch, as sort of a virtual colloquium appropriate to mathematics undergraduates as well as faculty. To start with we'd probably not want to launch into a lecture series on a single topic, but instead show high quality colloquium talks. I'm looking for links to things like Voevodsky's lecture "An Intuitive Introduction to Motivic Homotopy Theory", for example. (We give only the title here because links to YouTube aren't allowed on MO. If you intend to answer this question with a YouTube link, instead please type the title of the talk so it can be googled.)
We intend to start with MSRI talks and ICM lectures, but would like to know which are the best quality talks in these collections!
So by now you've probably figured out that the purpose of the current question is to collect other high-quality online colloquium talks:

Question: What is a link to your favorite online talk suitable for (reasonably) general audiences, that is not part of a lecture series?

It would even be useful for us if you provided a recommendation for a particularly high quality talk found in the MSRI or ICM archives, as all of these talks are not created equal. 
Thanks in advance for allowing us to benefit from your experience!
To clarify how this question is different from, for example this one, I'm looking for specific lecture recommendations and not only general collections of lectures. The hope is that the community can share its good taste in order to benefit our virtual colloquium (and help other departments who might want to try this).   
 A: Not sure if public lectures count, but I've always been fond of
http://www.gresham.ac.uk/lectures-and-events/multiplying-and-dividing-whole-numbers-why-it-is-more-difficult-than-you-might
(Gresham Lecture in 2007 by some descendant or other of the author of the Complete Plain Words)
A: For a lighter topic, Mathematics of Juggling by Allen Knutson is great.
A: Look at the web page of Carl Bender. It contains some remarkable colloquium talks and
lectures (videotaped) on the boundary between mathematics and physics.
http://wuphys.wustl.edu/~cmb/
A: My favourite is Bar Natan's talk explaining why ancient Celts should have discovered Witten's construction of the Jones polynomial.
"Cosmic coincidences and several other stories", http://www.math.toronto.edu/~drorbn/Talks/Tennessee-1103/
A: If applied math is allowed, here's one about invariant manifolds and interplanetary superhighway (Restricted three body problem)
http://www.podcast.ethz.ch/episodes/?id=1269
A: For specific topics, I found very high quality and worth watching videos at the Arizona Winter School. Those are yearly 5 days schools around arithmetic geometry, providing 4 lectures with one daily session, videos and notes, so it is a bit of a lecture series, however they are short, willing to be pedagogical and introductive, hence the first talk of a topic is probably suitable for a lunch colloquium.
