One of the most daring resistance operations of World War II was the 1944 sinking of the Norwegian ferry Hydro, with its cargo of heavy watter destined for the Nazi's secret atomic bomb project. Hitler's Sunken Secret features gripping first-person interviews with the sole living Norwegian saboteur and survivors who were aboard the Hydro when it blew up. Among the NOVA team's startling new discoveries is evidence that a second secret consignment of barrels eluded the saboteurs and made it all the way to Germany, but arrived too late to make a Nazi bomb feasible. WGBH Boston Video  (NOR63, $19.95)