This story is told by a Korean friend of mine. She said it's a true story that happened to a film director back in Korea a while ago.
There is this ghost movie that they are filming, and as a prop, they found an old abandoned house in a deserted area. One day, during a break away from filming, the director went into a room to have his break. As he was drinking coffee, he saw a girl dressed in white floated past the window. Thinking it was just one of the actresses, he gave no further thought to it. Soon after that, a crew member came into the room and they talked for a while. The film director enquired who was the girl dressed in white and the crew replied that there was no girl dressed in white required for the scenes of that day. He then realized with alarm that he was on the second floor of the house and there was no verandah outside, which means the woman must have been walking on air!
Talk about a truly spooky movie!