I’ve heard this term mentioned numerous times in the media, but what is it?
B-roll is footage that relates to the current story that is cut to intermittantly while the reporter is giving his shpiel. For example, if a reporter was covering a car accident, you’d have some B-roll shots of the street and piled up cars, which you would show while the reporter says what happened.
The term comes from simple two-source editing systems, in which your “A” roll was the report, and the B-roll was spare shots that you could cut away to.