I never used to like YouTube and I'm still not impressed with it. I think this is because the only thing I hear about YouTube is stupid teenager stuff that they video tape to pass the time.
However, I do like TeacherTube. It has showed me lots of cool videos. I used one in TECS 290 that was about a kindergarten teacher and how she dresses up on a daily basis based on what she plans on teaching that day. The day she was recorded, the class was going "on a bear hunt," so she dressed up as a warrior/hunter. It was really cute to see this.
I think TeacherTube can be very useful, and possibly YouTube if used correctly.
There have been many times that friends have emailed me videos from youtube but never did I know of Teachertube until this class. I looked through this website and even found a video that helped me with a formal teaching I did for my math/science methods class. Both these sites I have found to be very useful in the classroom and plan to use them in the future.