From “The Queen” to “Bobby,” from “Good Night, and Good Luck” to “Flags of Our Fathers,” more and more movies are integrating documentary footage with dramatic footage. The use of old footage is nothing new. “But what’s significant about these movies of late is the way they use archival material. Rather than as gimmickry, or shorthand, filmmakers are choreographing full-on tangos with the past. They’re — almost literally — dancing cheek to cheek with history.”