seek truth and report it

I think what it all comes down to is "seek truth and report it."
Which means that even when the truth isn't 100% laid out for you to write down, photograph, record or tape, a reporter should be searching for new ways to find or to present information. If a photographic moment has passed, you'll need a replacement photo that shows what happened afterwards; if a source isn't available for a quote or won't answer questions the way you wished they would, you have to make do with what you have and look for other sources elsewhere; if you can't get quality video that captures an ideal moment you have to get creative B-roll from somewhere else. Journalism is about investigation, creativity and thought.
Staging is unacceptable, whether in photos or in video. And if you're taking a picture with lights and other equipment that affects the visual aspects of a situation, its a photo illustration— and should be noted as such in your work.
Journalistic ethics come down to common sense, really— don't mislead the public, and have honest, well-meaning intentions throughout your work. Not staging visuals is a large part of that.