Applied Animation: Documentary research pt.4

B-rolls.  In film and television production, B-roll (B roll, or Broll) is supplemental or alternative footage intercut with the main shot. In addition to establishing shots, you'll also want to get secondary footage called "B-roll" - this can be footage of important objects, interesting processes, or stock footage of historical events. B-roll is important for maintaining the visual fluidity of your documentary and ensuring a brisk pace, as it allows you to keep the film visually active even as the audio lingers on one person's speech.
In our documentary, we'd want to collect as much car-related B-roll as possible - glamorous close-ups of shiny car bodies, headlights, etc., as well as footage of the cars in motion.
B-roll is especially important if your documentary will make use of extensive voiceover narration. Since you can't play the narration over interview footage without keeping the audience from hearing what your subject is saying, you'll usually lay the voiceover over short stretches of B-roll. You can also use B-roll to mask the flaws in interviews that didn't go perfectly. For instance, if your subject had a coughing fit in the middle of an otherwise great interview, during the editing process, you can cut the coughing fit out, then set the audio of the interview to B-roll footage, masking the cut.