Popular Culture has this wonderful list featuring a wide collection of some useful YouTube channels that you could probably recommend for your students. The channels suggested in this list cover various content areas and are arranged into two main categories: general and university collection.
Via Tom D'Amico (@TDOttawa)
youtube channel for teachers
Big Think, Google Talks, American Museum of Natural History, Edutopia, Library of Congress, YouTube EDU, and, of course, TED Talks.