Screenflow has a useful Markers feature for adding notes to the timeline.
You can use these to helpfully add a table of contents to your Youtube video, but unfortunately Screenflow doesn’t have the option to export them directly. Instead, use the free Subler program as an intermediary (download it from here).
Export from Screenflow with a chapters track
Open the file in Subler and export to text file
From there, tidy up the text file from the source