The list lets you download audio & video lectures from schools like Stanford, Yale, MIT, Oxford, Harvard and many other institutions. Generally, the courses can be accessed via YouTube, iTunes or university web sites, and you can listen to the lectures anytime, anywhere, on your computer or smart phone. We haven’t done a precise calculation, but there’s about 50,000 hours of free audio & video lectures here. Enough to keep you busy for a very long time–something that’s useful during these socially distant times.