Public broadcasters face grave risks of losing credibility and trust through increasing commercialism of their work, says David Fanning, founding executive producer of the award-winning series Frontline. It is "shameful" he says about the ways some public stations use pledge drives to market products for local sponsors. "This is our deepest embarrassment as public broadcasters…we spend more of our energy and promotional time pushing programs that have nothing to do with our mission." Fanning delivered remarks at the annual James L. Loper Lecture in Public Service Broadcasting in November before an audience of public broadcasting leaders, community leaders, scholars and……