The IMDB Prometheus page has a longer clip of a fake TED seminar with the film's villain - a corporate titan responsible for the first androids (a nod to Cylons) ... over at Aliens.wikia they have detailed analysis based upon all the known material regarding the so-called Space-Jockey from the first film ... the really good trailer is this one, the international trailer:
Don't watch this third trailer unless you want to see them give away the store - pretty much the whole tale is told here [My story breakdown below]
Super spoilery: Seems pretty clear: Messages left by ancient aliens invite space-faring humans to come visit a particular place. We go. We get bad news. We are to be used to take the Aliens back to Earth (to rid it of humans or some other nefarious purpose) and the Space Jockeys are not friendlies, or if they are, they've been compromised through Alien exposure. If they seek to tie this story to 1979's Alien then the information will have been held closely by the android-building villain in 2023 and hence when "mother" the computer and Ash the android conspire to have the Nostromo land on the moon LV-426 in 2122 it will have been 99 years since the events in Prometheus happened
