Horizontal Movement - This is the increment measured in pixels that the Image/Video will use to travel between the the Left Hand Side and the Right Hand Side of the screen. If you put a positive number i.e. 10 in the box, the Image/Video will travel to the Right of the screen at a speed of 10 pixels per second, and conversely, putting -10 will cause the Image/Video to go to the Left of the screen at a speed of 10 pixels per second