“Innocence of Muslims” purported to be an online trailer for a film about the mistreatment of Christians in contemporary Egypt. But it included bawdy historical flashbacks that derided the Prophet Muhammad. Someone dubbed it into Arabic around the beginning of September 2012, and a Cairo newspaper embellished the news by reporting that a Florida pastor infamous for burning the Quran was planning to debut the film on the 11th anniversary of the 2001 terrorist attacks.

Then, on Sept. 8, a popular Islamist preacher lit the fuse by screening a clip of the video on the ultraconservative Egyptian satellite channel El Nas. American diplomats in Cairo raised the alarm in Washington about a growing backlash, including calls for a protest outside their embassy.

No one mentioned it to the American diplomats in Libya. But Islamists in Benghazi were watching. Egyptian satellite networks like El Nas and El Rahma were widely available in Benghazi. “It is Friday morning viewing,” popular on the day of prayer, said one young Benghazi Islamist who turned up at the compound during the attack, speaking on the condition of anonymity for fear of reprisals.

By Sept. 9, a popular eastern Libyan Facebook page had denounced the film. On the morning of Sept. 11, even some secular political activists were posting calls online for a protest that Friday, three days away.

Yes, this is the timeline I remember and the video was already causing major problems throughout the region.
The video may not have been 100% responsible, but it certainly did serve as a convenient excuse for those responsible for the Benghazi attack.