“Their Finest,” which screened at the Toronto Film Festival this year, follows a British film crew attempting to boost morale during World War II with a propaganda film after the Blitzkrieg. Director Lone Scherfig and stars Bill Nighy, Sam Claflin, and Gemma Arterton stopped at the Variety Studio presented by airbnb at the Toronto Film Festival to talk the comedy drama, chemistry between Claflin and Arterton and more.