Yes, you read it right, it's possible to download Youtube videos, convert them to high-quality MP3 and all that at just a few clicks of a mouse.
First, you need to download YouTube video, right? For that, you simply need to go a website called KeepTube. To find out how to use KeepTube, go to http://keep-tube.com/faq.php, it's very easy to set up. What I like about KeepTube is that it has a Firefox plug-in which lets you download directly from YouTube and dozen of other video hosting websites.
After that, you may want to convert the downloaded file to MP3. For that you can use a program called YouTube downloader. This program has the ability to download YouTube videos as well, but since YouTube constantly changes and improves their code, the program often can't download. However, the part of the program responsible for converting the video file into MP3 file works perfectly all the time. You can download the program here. Once you download and install it, all you need is to open it, select the "Convert" option, select the video file you previously downloaded using KeepTube, and hit OK button. Voila, that's it, you just got yourself a perfectly fine and working MP3 file that you can listen just like any other ordinary song.