That's true. In fact in the video, the man's lower legs are obscured by the chair and this poses little problem for the system. However, I would say that if thi

That's true. In fact in the video, the man's lower legs are obscured by the chair and this poses little problem for the system. However, I would say that if this was all that were required, they would have used a blank square. Instead, they provide cues that mess with the system's sense of scale, by having almost like a window into another, smaller scene, with vague, human-like images that the network presumably recognises as faces. A group of tiny faces on the top of a single set of legs very much does not look like a human.