It is put out by the Khan Academy (as seen on 60 Minutes last Sunday). This online educational site was set up by a man called Salman Khan. It all began when he was asked to tutor his cousin on some tricky maths problems online. He made a video using a doodlepad and then uploaded it to YouTube. He made a few more and suddenly people from all over the world began contacting him, telling him how useful his videos were to their learning. He kept making videos and soon millions of people were watching them. Today he has uploaded over 1000 videos, has Bill Gates as his main sponsor, and his videos have had over 162,000,000 views!
Check out the video below.