Well, the story was supposed to be a bit puzzling, but not as puzzling as to make people not understand... I'll go fix that.
EDIT: Alright, the last two scenes of the briefing which describe the parts you guys seem to be more confused with have been replaced with this:
QUOTE
The outpost that was hit was quickly overrun, but the Zerg didn't stop there. They kept attacking and we lost outpost by outpost, until we were left only with our base at the landing site.
and this:
QUOTE
Now, my only chance of survival is to reach our Spaceport and grab one of the ships we have in there. I pray that the Zerg haven't attacked and destroyed it, or all will be lost for me. But somehow, I know I will make it out of this hellhole. I am Lieutenant Sarah Kerrigan, and I'm the leader of this expedition.
Is it better now? Give me your thoughts.