Here's how you can play YouTube videos at a faster playback speed.
1. Go to the YouTube HTML 5 beta page and click on "Join the HTML 5 Trial."
2. Go to a YouTube video.
3. Click on the Settings button in the YouTube toolbar.
4. Click on the playback speed that you prefer.
5. You can choose from the following options: .25 .50 Normal 1.5 2.0
For more, see the original article at the link below.