  One fundamental issue is what mediums are to be included under the term "film."  Although "film" initially referred to the celluloid stock on which movies were recorded, restricting the term to just celluloid-based works would be unduly restrictive.  After all, many of the films we watch today are either recorded digitally or projected digitally or both.  Such works are clearly part of the same art form as celluloid-based films, so the referent of the term "film" has to be taken to include works made on both mediums.