In 2010 I was lucky enough to be a part of the first (and so far, only) Youtube Star Teacher program. We focused on the reasons behind using video in the classroom and the art of making it great.
Since then, YouTube has been further establishing its place as a leader in education. In October they announced the 2012 YouTube Next EDU Gurus. These educators are firmly creating a place for themselves as leading YouTube educators. They are using YouTube to create a global classroom and sharing their passions and knowledge about everything from linear algebra and science topics to speaking Japanese and the history of art masterpieces.
Take a look at their collective work and you will have a much bette understanding of the power of YouTube in the classroom.