What is b-roll typically used for in video editing?

B-roll is primarily used to provide supplementary visual content that enhances the storytelling aspect of a video. It typically consists of footage that illustrates the subject being discussed in the primary audio track, allowing viewers to better understand and connect with the narrative. For instance, if a subject is speaking about a specific location, the B-roll might include shots of that location, helping to visually reinforce and contextualize their message. This additional footage enriches the viewing experience by offering viewers a visual representation of the spoken content, making it more engaging and informative.

In contrast, other options like using footage to create transitions or enhance audio quality do not align with the primary purpose of B-roll. These functions focus on technical aspects of video production rather than the storytelling element that B-roll specifically supports. Additionally, while summarizing a main storyline is important in video editing, B-roll serves a more precise role in complementing spoken or narratively-driven segments rather than summarizing them. Hence, demonstrating what a person is talking about is the core function of B-roll in video editing.