I'm not 100% sure what you mean by "to teach how have a conversation using movies."
But here's a few of my thoughts on utilizing movies/TV shows/videos in the classroom.
1) Use the content as a common starting point for the class. Even low level students can absorb a lot of information through context, body language, and visual cues.
2) Use the film/TV show/video as a "cultural artifact" from another place. Talk to students about what they see, and how it differs from Korea.
3) Show the students something, then have them work in groups to paraphrase a scene. Stress to them that the idea is not to have perfect replication of the dialogue, but rather to recreate the underlying concepts. Then have them practice and perform their scenes.
4) Show the students a clip, but stop the clip at a crucial moment. Have students predict what will happen next. Then, discuss what happened and how it differed from their expectations.
5) Show the students something that is inspiring, informative, or provocative. Use this as a starting point for a conversation about that subject.
6) Use videos from around the world to bring in more variety in the types of English the students hear.
7) Take a clip or scene from something and remove the sound. Have students watch the video and create dialogue voice overs.
8 )Watch something that has some idioms or other language that has nuanced meaning. It's often valuable to see these used in context.
9) Use shorter clips as listening exercises. Students can fill in missing words from a script. Combine this with more holistic questions that check to make sure the students understood the content.
10) Have students listen to a video, but turn the TV/projector off so they can't see it. Ask them to describe what happened, then show them the video.
