One Ted T. has the answer to why my proposed solution to Killer of Sheep's IP problems won't fly:

The reason is that licensing is the purview of "music publishing" companies, who are usually entirely unrelated to the record companies. Thus if artist X were to sell a ton of CDs, because their song was heard in a popular film, the "music publishers" won't see a dime -- their profit comes only from the licensing fees.

Of course this is insanely stupid for the music industry as a whole -- they would be much better off to wave licensing fees entirely and sell more records. Then they wouldn't have to bribe radio stations to play their music... If the powers that be had any sense at all -- they would buy out and put out of business the music publishers, and set up a low cost, simple licensing procedure. It would still be expensive to license a band like The Beatles who don't need the advertising, and don't want people becoming sick of their music, but the rights for low selling artists, who could use the promotion, would be available for a song.

But this won't happen, because the music industry is tenaciously clinging to a nearly century old business model, and will continue to do so until most new artist start self publishing, and put the entire industry out of business for good.

And there you have it.