YouTube? For Teaching?
YouTube has a large amount of educational material in the way of video footage of demonstrations, tutorials, and experiments that are all around too unsafe or expensive to do in the classroom. With access to these videos online, demonstrations are available to show students things that their teacher might otherwise say, but be unable to expose them to. Some schools, for example, deem the "sodium experiment" unsafe to do in the classroom and limit teachers from performing it, but here we have that very same experiment shown from the safety of an online video, along with another video showing reactions of more group one elements, all without the cost of purchasing these materials either!
In addition, students are often eager for the chance to view videos in class -- they view this as a break from what is commonly the monotony of taking notes, quizzes, and tests. The videos presented to a class, whether informative, or for demonstration, can be entertaining as well as educational, and in the cases where they get a little "corny," students and teacher can come together and laugh while learning.