If somebody says: If we were able to attach one of our songs to a big budget motion picture advertising campaign, it was like attaching a rowboat to an aircraft carrier.
--- does it mean that he is speculating (it hasn't happened yet) that if they were successful at that it would be great, or is he saying that they did it in the past and he felt it was like attaching a rowboat to an aircraft carrier?
There were a few times in the past when they were able to get one of their songs used in a movie/as part of the advertising campaign surrounding the movie. When that happened, their song really took off! On their own, a song would float along in the charts like a row boat on a river. Associated with a movie, it was like hitching' a line to an aircraft carrier (huge and fast) and being pulled along by its momentum: a very fast wild ride into the ocean of the mass-market!!