It is illegal to copy copyrighted works without a license and/or permission from the owner. Whether you pay a fee or not does not matter if the person allowing you to download the movie did not have the right to allow you to download the movie.
I can't tell you from the facts in the question whether you downloaded something illegally. If you downloaded a copy of Iron Man 3 for free, it was most likely illegal. If you downloaded someone's home movie, it is possible the owner authorized the download. Similarly, I watched an episode of Brooklyn Ninety-Nine online for free - it is not uncommon for new television series to be made available for free online.
If the information available to you at the time of download make it unreasonable for you to believe you had permission from the owner, you could be liable for illegally copying the movie.
Answered on Oct 24th, 2013 at 8:47 AM