Well, i had songs published and sold in Italy and abroad or used in radio etc…and The thing is: the Tv or Radio must declare to PRO (Siae in Italy) music and other arts contents. They get the spot indicating who has the copyright for either music and video etc… specifying authors and publishers with forms they use daily. They do it for every content. So PRO then pays the authors.
If your music is licensed for a TV commercial, this will go automatically in that process and you’ll get the money.
i hope this could answer 