It's the age of online learning, but nothing beats the human connection - seeing a face, hearing a voice. Maybe that's why video lectures are so popular - they bring the convenience of the internet together with the communal nature of the classroom.
TED video lectures are amazing. The speakers are all so passionate, and each lecture gives you new insights that can lead to a new perspective. It helps, too, that the videos looks great - stunning HD, creative angles.
And TED lectures are proof that online videos don't have to be short. If the video is good, and the topic is interesting, people will watch videos of any length.
MIT Open Courseware lets you attend one of the most prestigious colleges in the world, for free, from your computer. Through the site you can sit in on actual lectures and classes in degree programs. And there's even a new degree, MITx, to give non-enrolled students credit for the work they do online.
And if you really want to enrich your online MIT experience, check out MIT World, which broadcasts video lectures from campus visitors. It's a collection of incredible thinkers and visionaries.
This site has hundreds of lectures from academics, business people and politicians. All of the video lectures are sortable by speaker, location, topic and more, so it's very easy to find what you're interested in.
Open Yale Courses let anyone, anywhere, sit in on recorded classes from Yale. The video lectures span all subjects and go back several years.
Academic Earth's aim is to extend "high-quality online learning opportunities to people around the globe" The site does this by aggregating video lectures from some of the top colleges and universities, and making many of them freely available online. You'll also find links to online degree programs and for-credit courses.
Browsing around Academic Earth, I especially enjoyed the video playlists, which feature lectures on various topics selected by the site's editors.
The Nobel Prize web site has an archive of video lectures from winners dating back to 1999. You can watch winners in every subject talk about their lives and their research.
At iTunes U, there are thousands of video lectures and podcasts from colleges and universities around the world. Teachers can also use the site to distribute documents and other coursework.
This video lecture is unlike the others on the list, but it is probably the most popular video lecture online. It features professor Randy Pausch talking about "Really Achieving Your Childhood Dreams," as he was battling terminal cancer. The video went viral and has been watched tens of millions of times, despite being over an hour long.