Great way to show YouTube videos in your classroom without all the distractions that surround the video (comments, suggestions, etc).
Copy/Paste the URL of the video you want to play (web address such as http://www.youtube.com/watch?v=-ulvv3YdtNs&feature=plcp)
Go to http://viewpure.com/ and paste the address...click 'Create'
You'll have your video play in a clutter-free new window!
If that link is not working, another site to use is SafeShare. It works in the same way as ViewPure.