Tooble is an awesome application for Mac 10.4+ which lets you to search and download any video from YouTube. You can later play the video on your video iPod, iPhone, or Apple TV. Tooble’s has a very simple user interface which allows you to easily browse YouTube videos through categories, searching, or with a direct URL, and select any video for download.
With just a single click Tooble downloads the video, converts it, and imports it into iTunes Movies library to be played or synced to your iPod. You can download Tooble from here.