Merge and finalize seems like functions I could use and have used a bit. (Had self coded sketchier c# app for that). It cut portion of replay to new file and had another option to merge updated file or another rpl to original. Basically just allowed working more efficiently on later sections of replay without having to wait like 1-2k frames each edit or do some teleporting.
So merging and finalize would seem quite usefull for me. Clones portion is cool and interesting concept too. Could try making replay with it sometime, but prob wouldn't use that function that often
So if you consider updating or reviving some functions, there's at least another player too that could use some of the functions :D.
Anyway great job on it!