When you are watching a video on a small screen, like an iPod Touch or other MP4 player, which do you think is more important the images or the sound?

When you are watching a video on a small screen, like an iPod Touch or other MP4 player, which do you think is more important the images or the sound? Why?

The images because sometimes everybody want to watch a video or a movie on it. Everybody can't see it because the screen is too small.