Martin sez, "During a recent stay at our cottage in norther Wisconsin, I awoke to find this balloon hovering above a futon in the corner of the room. It was eerie. I didn't know what was going on for a second or two. There was no air movement, even though all the windows to the cottage were open. Perfect neutral buoyancy!"
The video is awesomely David Lynchian -- something about the cottage decor.
Hovering Balloon (Thanks, Martin!)