There is a baby monitor video that shows a kid lying in bed, eyes wide open. Suddenly you can see an apparition in the shape of a cat move across the floor and jump towards a window. Shortly after, the mother enters the room, asking the kid if there was a cat in the room. I can't remember what the kid answers, but they then tell the mother that there was a monster in the window.
I don't usually believe in ghosts, but videos like this make me wonder.
Also that old home video of the couple observing ghostly figures moving across a ridge at Ghettysburg...