I caught this video on Geekologie, and it made me laugh. This is a brilliant idea: a woman put a camera on a hula hoop, and then, well, hula'ed:
[WARNING: some folks might feel ill watching this. I will not be blamed if you have to wipe vomit off your keyboard.]
[Note: at the end of the video there are links to other videos like it.]
I found this fascinating. For one thing, the motion is slower than I would've expected. I suspect that may be due to an illusion when you watch from the outside as a hula hoop being used; humans are notoriously poor at judging rotating reference frames. After all, people still try to argue with me that centrifugal force isn't real, when it it quite clearly is.
Even more amazing to me was that I didn't get ill watching that video. I tend to get a seasick on a kid's swing or when reading in a car, so the fact I was fine watching this is weird. But I have pretty good 3D spatial reasoning, and have a lot of practice swapping reference frames -- trying to figure out when the Moon rises, what configuration planets are in, and how to point a telescope give you a lot of practice there -- so maybe that helped. Beats me.
But I wonder what other weird change-of-frames would benefit from using this camera technique? That might make a fun series of videos.