Refactor operations to support multiple runs without issues/inefficiency

[StevenTammen]

For example, if topic transition segments have already been standardized to 3.00 seconds, running the script to standardize their length a second time should not operate on the video files with ffmpeg if they are all already 3.00 seconds long.

This holds across all the various operations. Multiple runs should "just work" without casing any issues or bad state.