B-roll is video, image or audio content that illustrates a concept or noun that’s referenced in your “A-roll” (your primary storyline).
For example, someone you are interviewing mentions how they fought on the beaches of Japan–B-roll could be video footage of your interviewee flipping through a photo album or a sound recording of water crashing on a beach.
Another example: let’s say you interviewed the CEO of the company about topic X.
You could obtain relevant B-roll film by walking through the company’s offices and capturing the ambience and vibe of the workplace, as well as trying to capture the visual and audible subject-matter that you discussed in the video.
What’s the benefit of B-roll?
Voice-overs are excellent examples of this.
The reality is video footage of someone talking is boring.
Or at least it’s not as interesting as it would be if you provided video watchers some diversity of stimulation by showing them what the interview’s subject matter is.
So why capture B-roll last?
When we say “capture B-roll last”, we mean that you will capture your “A-roll”–and you will know what B-roll to go out and capture (whether that’s on video, with a mic, or scrounging online for content to supplement your storytelling).