First of all, congratulations on starting your teaching job. You have started out with exactly the right approach by focusing on your students’ needs.
When students tell you what their needs are, they are coming from a place of not fully understanding what learning a language entails. Sometimes students set themselves unrealistic goals because they do not understand the nature of language use and learning; this is totally normal. The skill that is required to watch a film and understand it is listening for gist. Gist listening is where somebody listens in order to get the main idea of what is being said without focusing on specific details and without hesitating over unknown words. Students are often reluctant to practise listening for gist; many of them think it is essential to understand every word that is said. I suggest that you start out by explaining this to your student. You need to dig a little deeper into exactly what he wants. His objective is not clear: understanding a film and understanding all the language used are two different things. Try to find out what it is he wants; he maybe wants to practise both listening for gist and listening for specific information but they are two different skills and therefore two different approaches are needed. I think it would be unrealistic for an intermediate student to understand all the language used in a film. I am an educated, native speaker of English and I sometimes hear words in films that I don’t understand. This may be because I am unfamiliar with the context, because the actor’s accent is unfamiliar or because the language is technical or specific to a region.
You can look at these posts where I have described gist listening exercises (which I think is your student's aim):viewtopic.php?f=2&t=1398 viewtopic.php?f=2&t=559
After speaking to your student and clarifying what it is he wants to learn, if you find out that he isn’t interested in gist listening, then please feel free to write in again for more ideas.