It doesn't matter if it's a CD, a Film, or manual with the instructions to build a spaceship. If you copy it, the original owner doesn't lose anything. If you don't copy it, the only one missing something (the experience) is YOU.
Enjoy!
Of course, if you happen to have some extra money for donations to creators, please do so. If you don't have that, try contributing with a review somewhere or recommending the content, spread the word. Piracy was shown to drive businesses in several occasions by independent and biased corps (trying to show the opposite).
It's especially true if you do it for archival copies of content you've already purchased.