The MFA's Boston French Film Festival, like all such events, tends to ease gently into the more challenging material on the program — so it's understandable that it kicks off with this comforting charmer instead of, say, Jean-Luc Godard's Film Socialisme. Philippe Le Guay's '60s-set Gallic Upstairs/Downstairs has all the requisite elements: easygoing political correctness, staid platitudes, saucy comedy, and a romance between a middle-aged bourgeois and a life-affirming babe 30 years his junior. The former is Jean-Louis (Fabrice Luchini), a buttoned-down stockbroker with a gawky wife who suddenly notices the stinking drains on the sixth floor of his town house. That's where the immigrant Spanish maids live, and his new awareness might have something to do with his new housekeeper, the stunning Maria (Natalia Verbeke). Next thing you know he's hiring a plumber, dissing Franco, and ogling Maria's ass. Vive la Revolution!