I am not sure exactly who said it. Does it really matter? The eyes are the window to the soul. So be sure we can see them on camera.
Do NOT look directly into the camera but do keep your focus up and out. In taped auditions, I am surprised at how often actors choose to look directly at the ground, as if they are thinking about what to say next. Check yourself. I bet you have done it before. Right? In that aw-shucks kind of moment, where you go from being in the moment to suddenly playing at being shy or unsure. But, it’s not authentic. Acting is playing the role of a truthful and honest character in an imaginary set of circumstances. I need to buy it--100%.
Also avoid making your eyeline too far to the left or right, so that you play the scene in profile. I want to see your face, your eyes, and your reactions. If you are speaking to someone sitting next to you, place that person in front of you slightly to the left or right of the camera. It may sound obvious, but I see this choice made frequently.
Set yourself up for success.