FacePause - Look away to pause YouTube videos
Yout - YouTube to Mp3 Converter
CornerTube - Watch YouTube in picture-in-picture on iPad
Softorino YouTube Converter - Download YouTube video & audio. Watch and listen offline
Video Hub App - The fastest way to browse, search, and manage videos on your computer. Like YouTube for videos on your computer!
You-Get - Command-line utility to download media contents from the web