I am not exactly easy to scare anymore. When I was a kid practically everything frightened me but I have grown up to be a gorehound horror fan who is easily bored and angered by "found footage" movies. I have a personal vendetta against The Blair Witch Project and I sincerely believe anyone who found Paranormal Activity scary is a little bit stupid. (Oooh, arguing and sleeping, I'm so scared!)
WNUF Halloween Special fucking got to me. It got under my skin. It was creepy and unsettling and even though it was chock full of unpleasant characters I was on the verge of tears by the end. For some reason this one succeeds where many others fail.
Watch it, watch it, watch it, watch it, watch it! (Even if you're not into the "Geraldo opening Al Capone's vault" style investigating-a-supposedly-haunted-house news story angle, watch it for the spot-on 1987-style local commercials. They're beautiful. They are perfectly imagined little globules of the past.)
End of line.