In "Walking Meditation" as the visitor walks past the camera his/her body is 'scanned' resulting in an image showing the pieces of the body as they were when passing in front of the camera. The longer a body part stays in front of the camera, the more it is stretched horizontally. The horizontal spacial axis is now the time axis. You are seeing how a thin sliver of pixels/space changed over time. The quicker the body part passes in front of the camera, the more it is compressed.