It's a good point. But, and I stand to be corrected by those with degrees in the field - it actually addresses the sort of tunnel vision effect in visual perception that occurs when one concentrates/focuses on observing a particular event. So if there was a bus with people hanging out the doors and windows driving down the street one might not notice many other things. If they'd said just watch the video, far more people would have seen the bear. Related to this is why when watch keeping aboard ship one doesn't normally focus but rather sweeps with one’s eyes.
