"According to Tobman, who has worked with Beyoncé before, the challenge was to find a building in Los Angeles with a porch that resembled those found in New Orleans. Nothing like that appeared to exist, so the crew used the Fenyes Mansion, which houses the Pasadena Museum of History, and converted it into a Southern Gothic plantation. The property was an early site of film production in the region, first used by D.W. Griffith in 1912 for a film called When Kings Were the Law, later retitled The Necklace."
Music Architecture and interior design blog Curbed has an investigation into the production design on the Beyonce video. Look away now if you don't want to have your illusions shattered: