I think it's junk psychology to say that a woman becomes more attractive because those around her are fatter or worse looking. You either find her attractive or you don't. If you're in a situation where you want to fuck that night, and she's the best option, you may fuck her, but that doesn't mean you think she's hot. You're merely settling for the best option that night. I don't find her attractive by comparison - I don't see her as being plus-sized in the first place. I'm not attracted to fatties, and I'm not attracted to thin girls either. I found the girl in the video to be comfortably in the middle range, and had some size in the place I like it. And I found her face to be cute. I see her as more thick than fat.
"The best kind of pride is that which compels a man to do his best when no one is watching."