Steve Flammia, on the blog Quantum Pontiff, posted this remarkable and rare 1-hour talks by Paul Dirac in New Zealand :
[youtube http://www.youtube.com/watch?v=RJ2FsatUvUw]
There are four of his talks currently uploaded online. The first one (the above) is on quantum mechanics; the second one is on quantum electrodynamics; the third is on the Magnetic monopoles; and the fourth one is on large number hypothesis.
Surprisingly or perhaps not, there still is lots of interesting stuff in them especially to hear the finer points from the person who himself was part of the historical events of Physics.
Credits to Richard Smythe for digitizing them.