This Firefox add-on allows cinema-style viewing of YouTube videos.
Once you've selected the "YouTube Cinema" option, the video will open in a separate tab in cinema mode. Plus, if you have the automatic mode enabled, all YouTube videos will open in cinema mode by default.
If you'd like to watch a video normally, simply hold down the "Ctrl" key. And don't worry about compatibility issues - YouTube Cinema works on Mac OS X, Windows, and Linux. Try it out today for a unique viewing experience.
Version 4.7.2: N/A