I think what happened is, there was a plan concocted ahead of time to address the situation if a terrorist attack were to occur on 9/11. The State Dept. already knew about the stupid video, and had it in the bag to pull out in the event something were to happen, which did in fact happen, first in Cairo. So the embassy in Cairo issues an apology immediately, and a few hours later the consulate in Benghazi is attacked. The meme about a video is already out there, and is seized upon by the White House.
I think that’s what happened.
Yes, obviously they knew about the video - but, none the less how on earth did they expect to get away with the lie that the video caused this... when they also had to know that there were NO DEMONSTRATIONS going on anywhere that were already claimed by foreign demonstrators to be the cause of their actions?!