Christophe recently did a tv spot where he talked about his new single, and the story behind it. The video below has English subtitles (and several bad puns on his song titles, which don't translate at all, lol). You'll also hear a sneak peak of the English version of "Berlin", which will likely be released as a bonus track when the album comes out. In other interviews, Christophe has said that the song is about letting go in a place where pleasure is everywhere, and nothing is forbidden.
Berlin is currently #22 on the French charts. Apparently the music video is being shot this week - I'll make a subtitled version once it's been released.
If you want to download the song (legally!!), I was able to do so through the website Starzik for 0,99€. You may have other options, depending on where you live, but many sites require that you live in France.