This article seems to imply it must be a craft of some kind, but I'm not convinced natural phenomena can be ruled out. As an example, ball lightning is still no

This article seems to imply it must be a craft of some kind, but I'm not convinced natural phenomena can be ruled out. As an example, ball lightning is still not particularly well understood and behaves in rather peculiar seeming ways. The speed that this 'object' moved at makes much more sense if it's entirely electromagnetic in nature.