You Tube (http://www.youtube.com/) is a very large video-sharing website. It can be used for many purposes including personal and educational use. Much of the content on You Tube is posted from private users that is meant purely for entertainment, but you can also find more professional videos that are meant for the purpose of education.
I do not have much personal experience with You Tube. Most of the experience I have had with the video-sharing website is hanging out with friends looking for funny or entertaining videos to watch for fun. I have yet to use it for an educational purpose. This is due to the fact that the site is blocked from our Howard County server. This creates a big problem for teachers that want to use it in their classrooms. I have, however, seen it used at professional development meetings for educational use. Other teachers have used videos from You Tube to get a message across to us in a training.
I plan to post my Public Service Announcement from our last class on You Tube. I have never attempted to post anything to You Tube so I'm sure it will be an adventure!