A user described scanning a 10TB home server with the free Krokiet tool and clearing about 900GB. Hash comparison for identical files and searching for similar videos are different functions, with video comparison requiring FFmpeg. The reclaimed space included movies in different editions or resolutions, so similarity alone does not establish that a file is an unnecessary copy. This is an individual case of selecting originals and backups to retain and reviewing results, not an expected savings figure for every storage system.