What are these bizarre sounds coming from the sky in countries from…

What exactly are we hearing in these YouTube videos posted by people who claim they've recorded ear-splitting roars coming from the sky with no explanation? Here you can see one of the latest, recorded in Budapest, Hungary last week. Conspiracy-lovers are calling them "apocalyptic sounds." Whatever they really are,… » 1/16/12 7:40am 1/16/12 7:40am