The AlphaEnable setting only comes into play when you draw to the screen or bitmap. It determines whether what you're drawing to it alpha blends or not. With it disabled, the pixels of the object you're drawing replace the pixels on the screen/bitmap. With it enabled, they blend together. So, unless you have a need to overlay multiple bitmaps over the same area of the screen, you probably always want AlphaEnable set to False on the screen when using it with the roVideoPlayer. If you do need to overlay multiple bitmaps in the same area of the screen, then you may have better luck blending them to a separate bitmap first, then drawing that to the screen.