I think YouTube is a fantastic tool to not only engage students but to also use through out learning experiences to explain different topics. Teachers would have to be careful how they displayed the video's and ensure that students didn't have access to other video's that may be inappropriate.
YouTube. (n.d.). YouTube company profile. Retrieved August 20, 2009, from http://www.crunchbase.com/company/youtube
Kearsley, G & Shneiderman, B (1999). Engagment Theory: A framework for technology-based teaching and learning. Retrieved July 29th, 2009, from CQUniversity e-courses, FAHE11001 Acitive learning & learning diversity.