Pretty much any musician will have their own music on their iPod, especially songs they're still working on. There are two reasons for this:

This is the way I feel about the My Teacher Is An Alien quadrilogy.

Put the bunny back in the box.

They should make two versions of these movies
I understand the appeal of making a visual companion to a novel, but if ever there was a source material that needed to be shamelessly mangled, this is it.