Saw this in better quality yesterday, looks CGI'd.
It could be a cloud of methane filled soapbubbles, but that is a guess. The cloud would have broken up doing the turn at 0:55. Problem with UFO's is, even if you see one for real with your own eyes, then it still looks like CGI projected in the sky. From what I know about CGI, you have to be really good and spend a lot of time to make it look this realistic.
Found a higher quality one. Goes up to 2160p resolution. :