Which action does not affect timing when editing a video?

Overwriting a clip does not affect the timing of the overall video timeline because it replaces the original footage with new footage while maintaining the same starting and ending points within the sequence. This means that the duration and placement of the clip remain unchanged, allowing the edits to fit seamlessly within the existing context of the project.

In contrast, actions such as inserting a new clip or removing a clip directly alter the structure of the timeline by adding or taking away content, which can result in shifts in timing. Moving a clip can affect the timing of elements around it if it overlaps or intersperses with other clips, leading to a change in how they sync with one another. Each of these actions impacts the overall flow and continuity of the project, while overwriting only swaps out content without changing the timing framework of the edit.