Who has the rights to the music? If I license a song to a videogame, and the devs decide to allow Lets plays on the section with my music, do I lose the right to avoid public performances of my content by other for money?
Depends on the terms on the license, I've seen licenses that assign full,
exclusive rights to the publisher, and licenses that assign minimal, single-use-case only licenses.
The terms of the license define what may be done with the material, in some cases musicians have assigned rights that makes their
own, future use of the licensed material difficult.
License / Music Industry lawyers are worth their weight in gold when you use them.
(Don't get me started on recording contracts from the big names, some of those are
fantastically evil, and yet still get signed by dumb kids with a "dream")