The program takes input from the webcam and determines where the circle will be placed based on the color values of 500 random pixels selected from each frame of video. I watch this and try to follow the circle with my pen (which is difficult because the video is flipped), and my actions in turn affect where the circle is placed because the video input changes as my hand moves and my pen leaves a line. So the drawing is responding to a stimulus which is responding to the drawing. Done in Processing. The frame rate for the screen recording is different than the frame rate at which the program was running so sometimes the circle doesn't appear for a few frames.