It began as a set up reason to explain the protest-turned-attack on the Cairo embassy. Which they knew as early as August was going to happen. There were two or three main reasons for that protest and none of them were "the video." One was to demand the release of the Blind Sheik. Another reason was anger that an Al-Qaeda leader had recently been snuffed by a drone thus the "0bama we are all Osama" signs they carried. There were also a number of protestors who wore Guy Fawkes masks, something associated with American and European anarchist-socialists (like the OWS freaks) not Muslims.
For some reason 0bama and Hillary wanted the press to blame something other than the real reasons for the protest.