D.C.’s own ADD filmmakers Mark Ruppert and Liz Langston are back tonight to present the first evening of their 5th annual 48-Hour Film Festival at the AFI Silver Theatre and Cultural Center. Screenings kick off at 7 p.m., and run every night this week through Friday. Like previous years, the festival invites amateur filmmakers to compete in a contest where they are given one character, one prop, and one line of dialog they must include,…