If Aderet is renting the CD to me for 20 years, that means I have a contractual rental relationship with Aderet for the next 20 years. If the CD stops working after 5 years, they must replace it. If not, it was all a joke and never a rental.
IIRC, it’s written in the agreement.
On second thought, it’s not written in, but doesn’t need to be (what is written is the opposite – that the consumer is not liable for breakage).
If the CD was defective, it would the company’s obligation to replace it (no different than a sale) but otherwise, if anything, it would be the consumers obligation (hence the exemption).