The demo video shows full screen scrolling, in which the entire screen updates smoothly. Also, LCDs require periodic refresh, so partial LCD updates require fr

The demo video shows full screen scrolling, in which the entire screen updates smoothly. Also, LCDs require periodic refresh, so partial LCD updates require framebuffer memory somewhere, often in the display controller built into the LCD panel or module, or less commonly into the pixels themselves. It's possible there's a frame buffer hiding somewhere, but plenty of systems don't have one, so the only option is always updating the entire LCD every refresh.