Originally Posted by Safe Bet
Some rights, not all and up for negotiation obviously.
I'm sorry but for one party to walk in here and assume 100% ownership over something that party did not 100% create is arrogant beyond belief.
Some of you people should be absolutely ashamed of yourselves.
Derivative works are legally defined as an original material that needs the copyrighted work to have material worth.
So yes, it's well established that you can make an original contribution to something and still not be square under the law. If I make a Terminator game, I'm clearly using all of the Terminator scripts, lore, visages etc to give the material worth to it even though I'd be designing all the levels and script.
The only workaround is distribute your work completely separate from the copyrighted work it's attached to - this is why making patches for games is entirely legal (as it should be), since you're not distributing any of the developer's copyrighted material with the patch itself, and requires someone to acquire their own legal copy of the copyrighted material. This is why books that dissect other books are legal (again, as they should be), because you need to get your own copy of the book it talks about yourself, and the study book does not distribute the original book with it.
In the case of an LP, this would mean distributing the audio of your Let's Play without any video or sound from the game, and requiring people to sync it up to the game themselves. Since that's near impossible, it's pretty clear that you rely on someone else's copyrighted material to give your own work material worth.