(I saw some of this on a different channel, but can't watch the youtube video for now, so I can't speak to the specifics of what was on that you tube video.)

I wonder if this is just a perception thing. I'm 6'-5" and when I use the keypads at gas pumps I frequently push the wrong button because the angle intended for viewing is set for a more average height.

With the voting machines I can easily see how viewing the screen at the wrong angle can cause a misperception of which button is being pushed. Ideally the people who designed the interface should have put the buttons side by side instead of vertically, then you wouldn't get that problem. I suppose it also wouldn't hurt to randomize the placement of the candidates, so one candidate isn't hampered by the lack of foresight of the interface programmer. Since a voter only votes once (in theory) the randomization shouldn't affect anybody.

The video I saw on tv, made it pretty obvious which voter was selected after the button was pushed. Anybody that misvotes because they weren't paying attention (not because of a disability) has little sympathy from me. Still the interface could be made more idiotproof.