Senator John Kerry could find his presidential hopes damaged this week when the 62 television stations owned or managed by the Sinclair Broadcasting Group carry a documentary about his antiwar activities 30 years ago. But the Democratic nominee for the White House may not be the only one adversely affected. Sinclair - the nation's largest owner of television stations, many of them in electoral swing states - is itself running a significant financial and political risk by telling its stations to pre-empt regular programming and carry the film. Already, Sinclair's decision has alienated some advertisers; enraged consumer and media watchdog...