cbs' tina kraus explains why families of missing passengers are angry and frustrated. [ screaming ] >> reporter: relatives of missing passengers protested outside malaysia airlines offices in beijing accusing authorizes of hiding the -- authorities of hiding the truth. this person, who lost his daughter and wife on malaysia airlines flight 370, said, we need real evidence to believe our loved ones were on that plane. we haven't seen it yet. families say they are confused over conflicting comments about the part of the wing that washed up on the french island of reunion. malaysia's prime minister says wednesday, investigators are certain the wreckage from mh370. but french officials, who are leading the investigation, cautioned more testing must be done to be sure. malaysia's transport minister says, the flaperon which helps keep a plane level and slow it down when landing has a maintenance seal that proves it belongs to flight 370. he says teams searching near reunion island off the coast of africa also found a plane window and some aluminum file that could be from the -- foil that co