Consider also that resolution is only one factor. Bandwidth is another. Digital movies are often full of compression artefacts, especially when there's a lot going on in the scene.
EDIT: Forgot to factor frame rate into the math. Divide that by 24 frames per second. That got me curious, so I looked into it and found they're using JPEG 2000 on each frame with no inter-frame deltas. Essentially like a constant stream of I-frames.