When it comes to some of the most unexplained footage of unidentified flying objects, there has been spectacular UFO film footage released from the NASA STS 48 Discovery Space Shuttle Flight. They filmed this original UFO footage between September 12 and 18, 1991. The top secret NASA film shows a UFO following after the space shuttle while it was in orbit during one of its mission.
NASA continues to refuse comment on the video even though it has come straight from one of the Discovery missions and it is most definitely at the top of the unexplained list. This footage has not been photoshopped, altered in any way, is very well documented, and has been the subject of an ongoing arduous scientific examination by multiple astronomers, scientists and space institutions all over the world.
The footage is available on YouTube and it is also below for anyone who wants to view it. The video appears to show at least a dozen objects moving around in an unusual manner. Along with that, what seems to be the most amazing part is when one entity is near the horizon and some sort of flashing occurs. It is then followed by yet another object that travels extremely fast across the field of view. After this, the first body takes off into space.