Good question - short answer is I've been focusing on finding collections that people don't know about, but I'm working on adding the MIT lectures - should be up in a day or two :)
I'd describe this as a discovery engine for lectures - the goal is to replicate some of the experience of browsing a library for interesting books (vs. traditional search, which is more about minimizing clicks between you and an answer)
I'd describe this as a discovery engine for lectures - the goal is to replicate some of the experience of browsing a library for interesting books (vs. traditional search, which is more about minimizing clicks between you and an answer)