Pretty cool video. The current explanation seems to be that it was a Russian rocket launch gone awry. Apparently there was recently aother rocket launch that went bad and had a somehwat similar appearance, but without the spiral.
The Russians deny that they launched anything, which isn't a surprise as the Russian military hates it when things don't work as planned.
Of course some of the conspiracy theorists are saying that it is part of Project Blue Beam. If you haven't heard of it, I encourage you to look it up. It's one of the craziest things I've ever heard of.