VinnPlayer

VinnPlayer is an application that you can use to watch and listen to any YouTube video without having to open your web browser - you can do it all from within the program.

It doesn't offer very many features. You can only search for videos, play them (fullscreen or in the window), and create a playlist (so long as you've registered).

VinnPlayer is an excellent program: it doesn't require installation, it's lightweight, easy to use, loads videos quickly, and allows you to create playlists. It's ideal for listening to music or simply watching a ton of videos without having to start up your browser.