Martha's Vineyard retiree Walter Cronkite's assertion that a Bush administration operative is behind last week's Osama bin Laden video has inflamed conservatives but left plenty of liberals wondering. ``I'm a little inclined to think that Karl Rove, the political manager at the White House, who is a very clever man, he probably set up bin Laden to this thing,'' Cronkite, 88, told CNN interviewer Larry King Friday night. Rove is the chief political adviser to President Bush and a figure Democrats demonize as a dirty trickster.Cronkite did not explain how he came to his conclusion, but the accusation had right-wing...