Check it out... TED-Ed (http://ed.ted.com/tour).

A primary focus of TED-Ed is to provide high-quality lessons taught by exceptional educators. You can see engaging videos to create customized lessons. One of our goals is to make the TED-Ed video library as engaging, thorough, and robust as possible. You can use, tweak, or completely redo any lesson featured on TED-Ed, or create lessons from scratch based on any video from YouTube. If you or someone you know is an engaging expert that you think should teach others, you can nominate them through our educator nomination form.