How do I remove the DRM from an Itunes movie for personal use?

I want to make a short edit of The Truman Show (a movie) to the song "Mr. Blue Sky", but if I try to use the file outside of hitting play in the iTunes app it won't work. My music works outside of the app, why can't I use the movie file I paid for and legally own? Every time I try to look it up the only thing I see is a massive list of probably virus filled suspicious links that I wouldn't click if you paid me. How do I remove the DRM or whatever it is breaking the files I paid for so I can use them as I see fit? And yes, making a compilation of the movie to a that specific song is fair use, as it shows both works in a new light by comparing them to each other, and by nature does not and cannot show the movie unedited in any way.