Film Editor
1. a person who practices film editing by assembling the [film] footage. However, the job of an editor isn’t simply to mechanically put pieces of a film together, cut off film slates, or edit dialogue scenes. A film editor must creatively work with the layers of images, story, dialogue, music, pacing, as well as the actors’ performances to effectively “re-imagine” and even rewrite the film to craft a cohesive whole. Editors usually play a dynamic role in the making of a film.
Source: Wikipedia