BOGOTA, Colombia (Reuters) - The FBI has obtained a videotape of three apparently healthy Defense Department contractors captured by Colombian rebels when their light aircraft crashed in February, U.S. officials said on Thursday. The tape, which was obtained by a television documentary maker and handed over to the FBI as evidence, shows the three clean-shaven American men inside what appears to be a house, one official told Reuters. The video is the first proof of life for the three men since they were captured by the Revolutionary Armed Forces of Colombia when their Cessna crashed on a rugged hillside on...