The importance of b-roll is a subject that we’ve addressed before, but it bears repeating.
First, a quick definition of what b-roll is. Once upon a time, video was edited non-digitally, using tape decks. There were often two decks: one that was labeled the “A” deck and the second the “B” deck. All the main shots, like interviews, were edited from the A deck; all the secondary, supporting footage – establishing shots or cutaways, for example – was edited from the B deck.
The secondary footage that was on the B deck came to be called the b-roll. Tape decks are a thing of the past, but the term b-roll is still used in reference to the footage that helps tell the story visually.
So the primary value of b-roll is to illustrate or enhance the messages being delivered in the interviews, but it also has a second importance – it makes the editor’s job a lot easier. The more b-roll an editor has at her disposal, the more flexibility she has in her editing (and the the happier she’ll be). The b-roll allows her to slice and dice an interview almost to her heart’s content, and then hide all the slices with juicy b-roll.
But, sadly, b-roll occasionally gets neglected. It’s not uncommon for a client to think of all the people who deserve to make an appearance on camera, and b-roll is perhaps not something that even occurs them. Rather than set aside a healthy chunk of time to getting the visuals, the tendency is to squeeze in as many interviews as possible, even if many of the people being interviewed are going to be saying essentially the same thing.
Usually, this is a mistake. We often argue that just as much time and effort should be given to getting that b-roll as to recording the interviews. Though it certainly doesn’t apply to all productions, a time ratio of 50% to interviewing and 50% to capturing b-roll is often just right. So rather than interview as many people as possible, it’s probably a better idea to eliminate a few of them and allot that time to capturing the b-roll instead.
Finally, don’t hesitate to stage your b-roll. You’ve got a professor talking about chemistry experiments, but his class meets at the end of the week? Get him to recruit a few students to come into the lab and mix up a few concoctions for the benefit of your camera.
For a comparison of a very short video with and without b-roll, see this post of ours from a couple years back.
P.S. The dude in the picture above is actually editing archival film of the Grateful Dead on a Steenbeck editing system. Though it’s film rather than video, the approach is similar to the video A/B deck system.