This movement is represented on screen as blocks of colour that leave behind faded trails of the previous frames of motion. Over the top of this will be laid a mask image so that this abstract paint image appears only within certain shapes. The 'painted' areas will not fade immediately allowing users to fill in larger shapes without too much effort.
By having a seemingly blank screen fill in with motion I believe this will encourage people to move about in silly ways and discover new parts of the image that they can fill in, and the nature of the way the paint is retained encourages occasional rapid motion. By encouraging users to search the screen for more parts it keeps their attention more than a mere visual gimmick would (e.g. the paint effect without the mask).