Their reactions really seem genuine. I laffed the first time I watched this!
http://www.youtube.com/watch?v=C_POYzwpRhY&NR=1
spoiler: At 1:06 you see the "ghost". It looks like a prank the first time you see it but if you stop and blow it up, it doesn't look so "joke" anymore. I saw it after a few times and messed with it after posting and realized this looked real and from the way it stood, I thought he hung himself. Went back and read the remarks and someone mentioned at about :52 there appears to be another ghostly effect. I looked at that and believe they're right. It would seem this person hung themselves and the residual haunting is at :52, and at 1:06 it is the same haunt walking upstairs....
This one might be for real.
NS
editted to add more info.