TED - one of the best sources for inspirational and educational videos online. TED started out as a conference around the topics of Technology, Entertainment, Design, hence the name. Since then, TED has expanded to include more topics and more ways to spread ideas.
Bright Talk - free webinars and videos for business professionals on various topics, including business management, human resources, information technology, marketing, and sales.
Solve for X - The talks explore radical ideas that may help in solving global problems and help billions of people. Solve for X is a Google project launched earlier this year.
Green.TV - dedicated to environmental videos. The site aims to create real change by educating people through videos and showing them how they can engage and act differently.
All Things Science - aggregates videos that revolve around Artificial Intelligence, Computer Science, Genetics, Green Energy, Oceanography, Philosophy, and many other scientific topics.
Khan Academy - Educational videos on math, science, finance & economics, humanities. There are also videos on test preparation for various test including SAT