Final answer:
To manipulate the playback of a video file during a presentation, you need to enable the 'playback controls' or 'media controls' feature.
Step-by-step explanation:
To manipulate the playback of a video file during a presentation, the option that must be enabled is the 'playback controls' or 'media controls' feature. This feature allows you to start, stop, pause, rewind, and fast forward the video at specific points. By utilizing these controls, you can effectively manipulate the playback of the video according to your presentation needs.