Here is a free version of a script that can convert YouTube videos to mp3. There are a couple of things you have to know before you host your own mp3 converting website.

- This script is not a complete themed website. It's just the engine to get you started.
- This script is served as is , I make no guarantee it will work for you , however it did just fine for me.
- This script is updated with the latest YouTube changes.
- In order this script to function you need a valid ffmpeg distribution according to your system (64 or 32 bit)

So your directory most be something like this :
-video2mp3/index.php
-video2mp3/YouTubeToMp3Converter.class.php
-video2mp3/videos
-video2mp3/mp3
-video2mp3/ (fmmpeg distribution here : ffmpeg.exe ... av-codec.dll , etc. )

How exactly this works? Saves the flv format on your webserver , converts it to mp3 , then gives a link to the generated mp3. Mp3's can be generated in 3 quality formats , Low , Medium and High.