No matter how hard they try, Hollywood's best have never really had a chance against reality: nothing they come up with tops what's really going on out there. (Though, to be fair, the real world doesn't always manage to finish the story within two hours, and the protagonists tend not to look as good as Will Smith. Steve Buscemi might be a liitle more accurate.)
Such is the case with Area 51. "Officially," the air base doesn't exist, but it's an open secret that there is a U.S. military installation at Groom Lake, Nevada; it's never been revealed what exactly goes on there, though. It's widely believed that the Groom Lake installation is where experimental U.S. aircraft are developed and tested--but many go beyond that. They posit that the base is the site of an ongoing collaboration between the U.S. government and aliens, that the experimental aircraft being worked on there is in some part extraterrestrial in nature.
That's all well and good; Area 51 has had its part in The X Files and Independence Day. Area 51 the documentary hopes to capitalize on that and provide the full story on what really goes on in the Nevada desert. Unfortunately, the documentary is far less interesting than the subject it hopes to illustrate; potentially interesting tidbits--how one ex-Area 51 researcher supposedly had his background erased by the government, the existence of a second, even more secret, base just south of Groom Lake--are few and far between, and even when unearthed, they're given a cursory explanation and discarded.