Sometimes I wonder if they even look at these scenes when they are slapping them together. It's could very well be just an innocent whoops. I mean, how could they not have noticed windows open vs closed when they splice in Reel B footage? I think they just don't care anymore (if they ever did)
More to the point, though, is that it shows the contamination possibility. Investigators, cameraman, and people wandering around. The quality on youtube isn't good enough for me to confirm or deny or even speculate whether or not it's the guy who wandered into the scene during the Halloween show, but whether it is or isn't doesn't really matter. There are more people on scene than meets the eye. Good catch, not sure how many points it was worth, but we'll make it equivalent to C-3PO sightings and call it 20!