Youtubefs enables a user to mount his/her favorite youtube videos as a local file system. YoutubeFS enables you to browse your favorite Youtube videos locally on your desktop without going to the youtube website. Just create a youtube account and add videos to your playlists, favorites list or subscribe to different channels. YoutubeFS then enables you to automatically load these videos to a local folder on your desktop. You can then view these videos (using a browser) as if they are local files.
Currently YoutubeFS works on Linux (Ubuntu 7.10) and Mac OS (Leopard 10.5.1). Please refer to http://code.google.com/p/youtubefs/ for details