This is oddly reminiscent of a question that an Adjunct Professor I know used in or around 2010 on a copyright law final exam :)
Assuming that you are not attempting to get licensed IP attorneys to answer your take home copyright final, you raise a number of extremely interesting questions:
1) Is your filming "fair use"?
2) What effect does the pay link have on your "fair use" defense? Does the fact that the link has nothing to do with the Harry Potter & Rowling have any effect on the fair use defense?
Given the complexity of these issues, and the fact that you are looking at major liability if you make the wrong move, I would recommend speaking to an IP attorney in New York. On the other hand...if this is a take home final; I would recommend really studying relevant cases dealing with fair use on the issues I raised above (as well as a few other minor issues, like what law governs, etc.)
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It's a ridiculous law school question. The most popular video of all time is a Justin Bieber video with 754M+ views. http://www.youtube.com/charts/videos_views?gl=US&t=a
And, it is nonsense to say a film of you opening up Harry Potter books has nothing to do with Harry Potter/J.K.Rowling. It is also nonsense to think more than a thousand would view such a video unless you did much more.
Do your own homework and research your own cases, please.
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The primary issue is whether your use of the Harry Potter trademark constitutes nominative fair use. That you posted a "click ad link" establishes that you were hoping to benefit commercially, which would tend to undermine any claim of nominative fair use. There are many subsidiary issues--including whether your video copied copyrighted images of the books and whether your video constituted unfair competition. Here is the bottom line from a practitioner's point of view (rather than a law professor)----anytime you attempt to profit by associating a video or other work that you create with a famous brand or celebrity (or in this case a combination of both), there is a very good chance that a Court would find that you are violating IP rights You certainly run a substantial risk of being sued by the owners of the trademarks and copyrights associated with the Harry Potter book brand---and such a suit is expensive. The outcome of such a suit probably depends on many facts and details that are not contained in your question---including at times just plain luck in selecting the right jury if the case goes to trial. In real life, most people would conclude that the risks associated with making and publishing this video are not worth the potential economic benefits.