Good for you, that people don't notice you looking at them. Unfortunately, things didn't go as well for me.
I am very aware of my environment, as well as socially anxious, so I tend to look at people through my peripheral vision. But when I do so, people tend to notice me doing this and they feel uncomfortable, talk to their friends about me, look away, etc. No, I am not being paranoid. I actually got bullied by people for looking at them out of the corner of my eyes! Some people even swear at me. I remember several years ago when I was in class, there's a dude sitting next to me and we're strangers. I did glance at him through my peripheral vision (not directly) so I notice him. But he must have noticed because he made a big deal out of it. He told another person, "She keeps looking at me, F--- her" and started fidgeting in his seat.
So you see, people do notice when I glance at them through the corner of my eyes, and my eyes aren't even that big. Have you ever heard of someone saying "I can smell your fear" or "I can feel your fear" even though you don't show it? It's as if they have intuition. Every human being is born with intuition, but intuition is stronger in some than in others.
As for the webcam trick, I will try it and see how that goes.
I know exactly how you feel. I noticed them placing their hands to cover their vision from me. I have to pretend nothing happens even though I knew they noticed I'm staring at them. At one point, I think some of the people trying to take a picture of me staring at them.