Why Don't Movie Poster Names EVER Line Up?

Movie posters list the stars' names across the top, and then usually a picture of the main characters right in the middle. But unless you already recognize them, you'll never know who is who because the order of the names is never the same as the order of the faces in the picture. What causes this? You're a smart person; I'm sure you can come up with the correct answer before the intro to this video ends. But the video is more than just the answer to the question. There's a lot of Hollywood information and history here, and quite a few interesting anecdotes.

Austin McConnell asks if there is a better way to design movie posters. My suggestion is that we go back to using real artists and their work for the image on the posters, like the example of Chinatown in the video, instead of the stars' faces. But movie posters are advertising, and studios will go with what works according to box office returns. (via Digg)