“The failure of an agency to identify itself as the source of a prepackaged news story misleads the viewing public by encouraging the audience to believe that the broadcasting news organization developed the information. The prepackaged news stories are purposefully designed to be indistinguishable from news segments broadcast to the public. When the television viewing public does not know that the stories they watched on television news programs about the government were in fact prepared by the government, the stories are, in this sense, no longer purely factual. The essential fact of attribution is missing.”