Here is a great way of converting a video from YouTube to Mp3, it is easy to do, simply enter the YouTube page address into the field provided on the TuneTune website and the rest is done for you, it is that easy!
These are the details for the TuneTune music conversation tool;
TuneTune allows you to easily convert a video from YouTube to MP3. Just submit the YouTube link and we will take care of the rest. We will convert your video to the highest quality available and as fast as possible. It’s possible to edit the ID3 tags after conversion, if desired.
Source [Tune Tune]