How to grade a film?

Since this is a free week for blogs, I am going to write about a conversation we had during class groupwork this past week.  In our group, we talked about chapter 6 of Miller.  To refresh everyone's memory, it had to do with creating a "found poem" and making a video based on the poem.  In the chapter, Miller talks about a teacher who integrates film into her lesson plans as a way to be "up to date" and stay relevant as a teacher in a digital age.  The biggest problem that I personally find with doing things like this is that I would have a hard time deciding on the best way to grade a project like that.
We talked about the possibility of writing a paper about what you did in the project, and what you learned about the work of literature by creating the film.  This poses a problem for me, though.  If you are writing a paper about what you learned about literature by creating a film, isn't the film just a sort of busywork then?  I think that the student would be able to write the paper on what they learned about the literature without doing the film.  This is not to discredit the idea of creating a film, but rather to think of a better way to grade the film itself, and not base a grade on the paper written about the creation of the film.
Obviously, the students will not have the abilities of Steven Speilberg or even necessarily know the first thing about film, but film itself is obviously a medium that should be studied and understood by students as movies and television are the way that most information is conveyed in today's society.  I think that the film should be graded not based on a piece of literature necessarily, but based on the understanding of how film conveys a message.  This would keep the lesson relevant, and not relegate the lesson in film to the "fluff" category.