As we say on the site, here is a explanation why we build this service:

The primary motivation behind Spotifytube was my friend that was trying to make an audio CD to play music in his car. He asked me for help because he has a Spotify premium account and can download all his tracks for offline use. We figured files are located on his hard-drive, but we couldn't find a way to access the encoded files containing the audio files.

We've been reading about how Spotify protects and encodes their music preventing users from downloading the audio files. We looked for a solution online, but it seemed there isn't any Spotify downloader available online. We figured we can find Spotify tracks on Youtube and convert Youtube videos to the mp3's without doing any harm to Spotify.

To our surprise, it worked so well that we wanted to give other people way to convert their Spotify tracks and make audio CDs to listen in their cars.