Looks to me like it might just be the way he was holding the tablet in his hand. I know when I'm showing other ppl things on my n810, sometimes my touches dont register and I think its because I calibrated my screen with the tablet in both hands directly in front of me. I have to pay close attention to the exact location of my touch vs. what I'm trying to select.

Not sure if I'm even making any sense but I think its just the way he's holding it.