Não me ocorre nome em português para B-roll, mas tem aqui a descrição do que é. Aliás, não percebo bem como se encaixa no contexto da frase. Se lhe for útil, já compensa o trabalho:

B-roll
B-roll or B roll is unrelated talk during an interview.
This technique of using the cutaway is common to hide zooms in documentary films: the visuals may cut away to B roll footage of what the person is talking about while the A camera zooms in, then cut back after the zoom is complete. The cutaway to B roll footage can also be used to hide verbal or physical tics that the editor and/or director finds distracting: with the audio separate from the video, the filmmakers are free to excise "uh"s, sniffs, coughs, and so forth. Similarly, a contextually irrelevant part of a sentence or anecdote can be removed to construct a more effective, to-the-point delivery. This can also be used to change the meaning of the speaker to fit the view of the producer. In fiction film, the technique can be used to indicate simultaneous action or flashbacks, usually increasing tension or revealing information.


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Note added at 33 mins (2008-03-05 19:14:49 GMT)
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Acabei de me lembrar: planos de corte.

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Note added at 38 mins (2008-03-05 19:19:49 GMT)
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» Five News acaba com planos encenados
JÁ TODOS vimos aquelas entrevistas onde são inseridos planos de corte, mostrando o entrevistador a fazer uma pergunta ao entrevistado. ...
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