Hi, Bob! In 20 to 40 minutes the most you can hope to do is introduce them to a a few basic ideas. Probably the most useful thing you could say to them is
Hey Pluk, I'm a huge proponent of capturing quality production sound although most of my clients never listen to me and then wonder why I have to spend so much
Hi Bob, ... It's great to learn from Hollywood Movies, but those tracks have their own set of problems. Your audience can't afford ADR or a microphone nowhere
Many DVD extras have examples. We had a discussion on this topic once before on this site. Below is one posting from Richard Stevens on the topic. Good