I guess you could say that all the music I listen to is a soundtrack of one sort or another. Soundtrack for cleaning the house, soundtrack for sleeping, for biking, for reading, for living. Most of my mixes could be considered to be mini soundtracks.
So what makes this one different? I guess the tracks collected here just sort of had that "soundtrack" feel when I first heard them. I imagined a scene from a film with the tune as the soundtrack. The tracklist then becomes a set of "imaginary soundtracks."