download them then convert them,I use Any Video Converter you can find it on the internet and its free to download.Also if you get your music videos from youtube you can download tubetilla and convert youtube videos to mp3. Then there are some that you can just change by renaming it with .mp3, but this way doesn't work most of the time.Another option:If you want to convert a Youtube video into an MP3 file, use the 'Youtube to Mp3' plugin for Firefox.
you will have to download it as an mp4. if you downloaded it as an mp3 it wont work
youtube mp3 and mp4 converter
Converting YouTube videos to MP3 files without permission is generally considered illegal due to copyright laws.
You shall not download any Content unless you see a "download" or similar link displayed by YouTube on the Service for that Content. Unless a download link is present for a YouTube video, it is against the YouTube Terms of Use to download videos/soundtracks from YouTube.
You can use Firefox add-ons " easy youtube video downloader" for your task.
You can download and install internet download manager from which you can download mp3 audio songs and download videos from sites like youtube just clicking the download button displayed on the video. If you are using Mozilla Firefox install an addon named "Easy YouTube Video Downloader" On Youtube below video you will see the download option and you can save the video into audio mp3 and other video formats as per your requirement.
http://hippomp3.com is great to download songs and youtube videos...
www.heepz.com
Yes It Is Legal , It is Only Illegal If You Were To Download Something That Is Copyrighted And The User Does Not Allow You To Download It. I Use It So Does A Million Others.
you can download audio straight off of youtube with youtube to mp3 converter wich is on cnet.com for free download,all you need is to copy the videos URL and paste it to the converter and it takes the audio
video2mp3.net lets you grab music from a youtube video and then turns it into an mp3 file which you can then download. BUT, bear in mind that unless there is a download link available on a YouTube video's page, it is against the Terms and Conditions of YouTube to download videos or soundtracks.