The Truth: What's actually moving in the background is a large exotic bird on loan from the Zoo. The urban legend started when The Wizard of Oz was released on VHS in 1989, and persisted over the decades, until the most recent Blu-ray edition of the American classic reveals the myth as false.
The Truth: The mysterious figure behind the curtain is a cardboard cutout of Danson's character wearing a top hat and tails; it was used as a prop for a storyline that was eventually cut out of the movie. The house is also not a real house, but a set on a soundstage in Toronto. THANK GOODNESS