No demonstration before attack on US Consulate, source says
"The intelligence source said no protests were happening before the attackers struck at about 9:35 p.m. local time last Tuesday. The account backs up claims by a purported Libyan security guard who told McClatchy Newspapers late last week that the area was quiet before the attack."
Report: Never an Anti-American Protest in Benghazi, Only a Planned Attack (CBS Video Report)
Here is the article by Alistair McDonald referred to in the article above.
US diplomats, Marine rescue team were also attacked at safe house, Libyans say Alistair McDonald Sept. 12,2012
Sounds more like a deal gone bad, or some kind of negotiations went totally wrong and Obama is trying to cover his tracks.
It could be there was a real wedding. It could also be a staged one to cover for somethingn else. I suppose a wedding crowd could be a good place to position attackers close by until they are ready, and the civilians would provide wilingly or not, good cover from return fire.