thank you but I do not understand why most you youtube bookmark creators, don't realize there might be need to create more than one timestamp for one video.

same as "YouTube Parts Looper & Bookmarker" ; "YouTube Timestamp Bookmarker" ; "YouTube Browser Bookmark Tagger" they all give you only one shot, after which you have to go into the library and rename the bookmark in order to make a new timestamp through the addon button.
defeats the purpose.

I might as well use ctrl-D and write the time myself into the title at that point.

great idea; poor execution. at least make it optional through a toggle in options.