B roll

• B-roll

B roll (usually uncountable, plural B rolls)

1. (television, film) Supplemental or alternative footage intercut with the main shot, used for example to indicate simultaneous action or flashbacks.
   • 2018 July 26, Ignatiy Vishnevetsky, “A documentary muckraker takes on the tech sector of health in The Bleeding Edge”, in The Onion AV Club‎:

     The Bleeding Edge isn’t an audacious or essayistic piece of filmmaking; it’s overstretched with talking-head interviews, montages of corporate videos, and creepy B-roll shots of hospital equipment.

• A roll