First of all, in most cases copying for your own ipod does not violate the agreement. Secondly, although that’s the producer’s only recourse, the renter, by violating the agreement, was oiver on g’neiva (using the producer’s property in a way which he never allowed).
Breach of contract is g’neiva? If I sign a contract with you to rent an office for business purposes only, but instead I move in with the gantze mishpacha, is that g’neiva? (Just asking.)
Your point is one of the things gained by rental vs t’nai: in a t’nai, some poskim (not all) maintained that the producer would have to refund the money (and since he has no intention to, the whole t’nai is invalid). Others hold that since the purchaser broke the t’nai, the money need not be returned.
You’re saying that the halacha for a rental is different than that for a t’nai, in that all poskim agree there is no need to refund the money for the remaining term of the rental, if the renter broke the terms of rental?
(Side point: It would be easier to read your comments, if you put a blank line between your paragraphs as well as your quotations.)