Don't worry about getting every word or sound right - focus on listening carefully, moving along quickly and keeping pace. After the movie ends, repeat the exact same movie and do it again. And again. By forcing yourself to speak at native speed, your brain becomes hyper-receptive to what you are hearing, and you will find yourself not only picking up the words quicker and quicker, but also unconsciously mimicking the inflections and vocal nuances that are usually difficult to learn for a non-native.