Answer:
add reverb, echo, or delays to the original track
Explanation:
By adding reverb, echo, or delays, Greg makes the soundtrack of his documentary more dynamic and interesting, mainly because he allows the music to shape the scene and the effect he wants to emit with the combination of the image and the video. By adding these effects, Greg allows the soundtrack to expose different aspects of himself, surprising the observer and listening to him, in addition to showing full mastery of video editing.