Ways to convert YouTube videos to MP3 are available both online and offline. As of May 2015, some websites that allow users to convert YouTube videos to MP3 include Clipconverter.cc, Youtube-mp3.org and Mp3fiber.com.
At Clipconverter.cc, paste the URL of the YouTube video you wish to convert into the field provided, then click on Continue. From the audio conversion formats available, such as MP3, M4A and AAC, choose the MP3 option, then click the Start button for the conversion to commence. After the conversion, which takes several minutes, click on the Download button to download the converted file.
At Youtube-mp3.org, simply paste the video URL into the field provided, then click on the Convert Video button. If the conversion is successful, a message saying that the video has successfully been converted to MP3, along with a download link, is displayed. Click on the link provided to download the converted audio file.
At Mp3fiber.com, paste the URL of the YouTube video into the provided field, then choose the quality you desire for the converted MP3 file. Next, click on the Download button to download the converted file.
If not interested in converting online, an example of an offline application that allows for the conversion of YouTube videos to audio formats, including MP3, is YTD Video Downloader.