It's unclear how you can be positive what someone else has done, as far as licensing rights. This use sounds like an infringing use if there's no license, and one that the rightsholder needs to enforce with a DMCA take down notice. This isn't a criminal matter, so if you're not the rightsholder, you don't need to report anything to anyone.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
Let me guess, you know the person that is using the movie and you don't like them and want to get them in trouble. I suppose you could do a Google search, find out which movie company has the rights to the movie and let them know. It's their fight, not yours.
If you didn't get Pamela and Laura's answer clearly enough: mind your own business and live and let live. Our legal systems are overwhelmed with real disputes - manufactured disputes created by third parties are unwelcome.