JTL I see, this gets confusing because there can be multiple things that dither, including OS X, Windows 10 Anniversary Update, Intel Graphics, and other GPUs.
I don't see a reason why dithering is enabled on OS X with no user option to turn it off? There's no reason to dither if the display is 8-bit.
I looked at the Amulet Hotkey PDF. If someone was able to obtain the .dmg, I think that'd disable dithering and we wouldn't have to use their video capture boxes.
A few years ago I filed a bug report with Apple Accessibility about an unrelated issue with an API call and it eventually got fixed. Maybe we can petition Apple to make dithering user customizable on OS X and iOS.
Does anyone know if Ubuntu does temporal dithering?