Funnily enough, I'm trying to do this, and just posted in "What are you Working On?" Not sure I'll have much luck if Apple couldn't make it happen though!
https://news.ycombinator.com/item?id=46268285
Uploading a copyrighted work, then editing it, and saving it into a new file is a clear case of making a derivative version of a protected work. There's no issue if it's Creative Commons allowed or Public Domain, that's just fine and I don't intend to say otherwise. It's when it comes to the nature of the source and the editing and saving that is, to me, just troublesome from a legal / academic standpoint.