Video lectures are sometimes frowned on as being too ‘canned’ or ‘talking head’-like. I think this depends on the teacher. Video lectures will become increasingly popular as talks can be more readily refreshed and recorded, as the technology matures.
Google is creating an archive of science and tech lectures online. There are some gems on Google video and related sites.
Related sites are also linked to, below.
Some of my favorites:
Hans Bethe’s physics lectures makes quantum theory accessible to anyone on Quantum Physics made Relatively Simple:
I suggest everyone take some time to read about his life on the “About” tab if you are not familiar with the man.
Interviews and lectures by Richard Feynman=
There are also some good lectures on biological sequence analysis, genomes, and semantic web (for instance) through Google.
Some bioinformatics-related videos
Some more off-the-beaten path physics:
More for experiments rather than lectures but the Journal of Visualized Experiments? is rather good.