You are invited to watch this video
and conduct an intellectual exercise. For the sake of this exercise accept the video shows extraterrestrial craft in near-Earth space (which it certainly could).
Then after your viewing consider this: there is a space station orbiting the Earth. On this station are a number of extremely advanced cameras surveying space (to not have such cameras would be very suspicious and bad NASA PR). These cameras send live video back to Earth (also necessary). The live feed is viewable by people over most of the world on a massive electronic, interactive delivery platform using computers more powerful than those that ran the Apollo Program. Millions in this viewing public own powerful software tools allowing for the editing of these videos. The interactive delivery platform contains massive social networks with collectively several billion participants to which such edited videos can be delivered in seconds, and the delivered videos can be shared and reshared ad infinitum.
None of this technology existed when the extraterrestrial presence truth embargo was planned and initiated between 1947 and 1953, and would not exist for decades.
Now, can you understand why a massive government disinformation campaign so successful between 1947 and 1991 could collapse in 2015?