Is scrolling in Metroid Zero Mission jerky because the emulator can't run the game full speed on the Wii or is it a case where the video output is not synchronized to the display's refresh rate?
Well, I'm now pretty sure the reason is the emulator is not running at full speed. At the beginning of the game when run towards the right it runs pretty jerky but when you eliminate the little animals crawling around the floor and ceiling, it runs smoother with the occasional hiccup which suggests to me it has less processing to do with only the Samus sprite being animated.