I am watching Roger Ebert’s commentary on the magnificent Casablanca. I once went to validate a quote and searched for best lines from this movie. A list of popular quotes reads much like the screenplay itself — no movement wasted. I have studied this movie not as a movie, but as a story. 
Ebert’s angle swings through periods of movie-ness (lighting, camera work, and so forth), but contains good notes on the story as well.
If you can get your hands on this DVD, I highly recommend it. If not, well, do what I did — have a resourceful friend :-)
Play it again, BDB.