UFO Mothership & Fleet Over London UK 24th June 2011 (credit alymc01) [HD] has as of 9:30GMT June 28 been viewed 710,431 times after being uploaded on June 26 and is ranked second on YouTube's "most watched today charts."
The video begins with shaky footage caused by what can be assumed to be the person behind the camera running down the street to where a group of people stand filming the sky on their mobiles. The camera then turns upwards, where three shining dots can be seen passing through the sky.
The circular dots then return several times before a similar larger shape appears, hovers for a short while then disappears at speed. In the background a man can be heard saying "There's a UFO up there."
The video was first uploaded June 24 by YouTube user alymc01, who despite being a member since 2007 appears to only have this video and a duplicate of it on his or her channel; the video that has gone viral is a re-post of that footage by user EllasVirgo.
The video has received some mainstream press coverage in addition to mentions on blogs specializing in UFOs. While no marketing company has yet come forward to claim responsibility for the footage, a number of similar videos have appeared on YouTube over the past few days, including
UFOs Over London Friday 2011 - UFO fleet over Tower Bridge London 6/24/2011 and UFO June 2011, leading some to question if the videos are part of a viral promotional campaign.
UFO Mothership & Fleet Over London:
http://www.youtube.com/watch?v=0AouX-nWvv4
UFOs Tower Bridge -
http://www.youtube.com/watch?v=wQmut0XtD3s
UFO June 2011 -
http://www.youtube.com/watch?v=fD7Ok9By6AM