B Roll should be part of your editing technique because the film on its own might be bland and boring without it. B roll is something that you use to add different little tid bits of information to. You sometimes need to cut away some parts or add to them and that is where B roll comes into play. You can insert additional shots into your main shot. You can also clean up or edit the pacing of the video with B roll.

Key Takeaways:

• B-roll is a lot like the seasoning or the side dishes for your main footage keeping things interesting with other angles.
• B-roll footage can be used to replace A-roll when their are problems or it can just be used to change the mood in a scene.
• B-roll can mean very different things from creating amazing transitions to showcasing the location of where you are filming from the edge of the space. Don’t be afraid to shoot lots of footage.

“B-roll, in a straightforward definition, is supplementary Footage or alternative shots used in a video”

Read more: https://www.premiumbeat.com/blog/b-roll-video-edit-guide/