Students in my class complain to me that watching films can be very difficult because of the constant use of idoms, phrasal verbs and slang. It’s true, this area of English or indeed any language can cause all sorts of problems but what can you do about it?
The answer is the same as always unfortunately – study. When my students want to study using a film, I always advise them that it is far better to only watch one or two scenes of the film at one time. I think it is important to have seperate notebooks for idioms/phrasal verbs and slang. Of course when you watch a film you need to have a good dictionary at hand and if possible, a phrasal verb dictionary also.
First watch the scene with the subtitles off and try to understand as much as you can. Next, watch with subtitles and make a note of any words or expressions you don’t know. You will need to pause the dvd often to check things. It’s also a good ide to practise saying the lines after you hear them. If you have some device for recording the scene use it. Listen to the scene on your headphones when you have spare time - on the bus for example. Try to memorise as much as you can and practise the lines with the correct intonation over and over again until you feel comfortable.
I once knew a student who improved her English dramatically using this method for the film Before Sunset with Ethan Hawke. The only problem was that it took her about three months to get to the end of the film!