By Robert Windrem, NBC News Producer U.S. intelligence officials are analyzing newly released video of Cuban leader Fidel Castro for clues about his health and political viability, NBC News has learned. The CIA has a medical intelligence unit that has long tracked the health of Fidel Castro and his brother, Raul, now the country’s president. But the CIA’s political analysts are equally interested in the new video, released Tuesday, since it also shows the two brothers interacting. Raul Castro succeeded his brother in February. Fidel Castro had last been seen a month earlier, meeting with Brazilian President Luiz Inacio Lula da Silva. ...( read more ) ...