Watch2gether is a neat site through which you can watch YouTube videos and host text chats about them at the same time. I've written about the service in the past, but it just got a facelift so I'd like to point it out again. It is really quite easy to use Watch2gether.
Use engaging videos on TED-Ed to create customized lessons. You can use, tweak, or completely redo any lesson featured on TED-Ed, or create lessons from scratch based on any video from YouTube.
Directory of the Web's best educational video resources. Includes 5min, Academic Earth, BrainPOP, Brightstorm, iTunes U, YouTube EDU, and many more sites.