This is too complicated to try to put into words, so there’s a screencast instead.
Video of the final product:
Video explaining how to do it:
In text form: C# code to convert a Harvest CSV extract into a node and edges CSV file. Then in Gephi, import the two files, convert the start/end dates into an interval, and set up the prettyness. Record a long video with lots of stabilization and then speed it up.