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.
To get started enter a nickname for yourself (it could be your real
first name) then search for a video or enter the URL of a video that you
have previously bookmarked. When you have found the video you want a
chat column will be present on the right side of your browser. You can
invite others to chat with you by sending them theURL assigned to your
chatroom. Together you can watch a video and chat about it at the same time.
Applications for Education
If you frequently use video clips in your classroom, Watch2gether could be a nice tool to use to have students share observations, ask questions, and answer questions while watching those clips.