When the Aurora is strong, you can see subtle undulations. It will hang down like a velvet curtain from the sky, subtly moving like in a faint breeze. When I was a kid, we'd whistle for the Aurora, to make it dance. But according to the folksy (and fun) superstition, you should avoid waving to it with a white handkerchief, lest it come down and sweep you away into the heavens, where you'd be forever trapped in the castles of the sky. Some would still wave white handkerchiefs for that very reason though, if for no other reason than to tempt fate. ;)

I've done a lot of time-lapse of Aurora, which accentuates the moves. These days, however, the ISO and light sensitivity of cameras has gotten so good that you can indeed film the Aurora at regular shutter speeds and still get a really good result. I think we'll see more interesting (and perhaps more scientific) presentations of the phenomena in the future due to that fact. Or one may at least hope!