This video seems incorrect to me, I read code line by line one at a time most of the time. The video seems to be showing that the eye is jumping all around.
Your eyes jump around a lot more than you think they do, no matter what you're looking at. Your brain compensates for the effect somewhat, so it's impossible to notice the full extent of the movement on a conscious level.
Consider that you can conceptualise reading code as a linear narrative even if your eyes tell a different story. Our perceptions of ourselves are often radically different from our actual behaviour. One fine example of this is in phonetics: the two /t/ sounds in “tomato” are quite different, yet we think of them as the same sound.
