The number of tools available for downloading YouTube is overwhelming, we see new tools for downloading very often. All these tools will allow you to download videos from YouTube and some allow you to convert to other formats. Youtube2Mp3 is a Firefox add-on that allows you download youtube videos directly as MP3 files.
Install YouTube2mp3 Firefox add-on, this is an experimental addon so you need to login to mozilla site before you could download. Whenever you want to download a video look for the convert & Download as MP3 link just below the URL and Embed code in the sidebar. If you click this link it will open a new page, and will convert the video and opens the save the file dialogue.
This is the simplest method to download extract music from youtube videos, you don’t need to navigate or special software just the extension for Firefox will do. If you want to download Videos check out downloadhelper extension and for downloading videos as MP4 files check this bookmarklet.