This app is to help you find missing files from your sequentially downloaded files. E.g. you downloaded 100 or 200 episodes of any video/file which are all numbered like "some video 1.mp4, some video 2.mp4". If for some reason one or multiple videos are missing you won't have to manually check which are missing. Just select all the downloaded files at once and fill in "File Starts At" and "Total File". The app will show all selected files and missing files.
The app takes the first number it finds in the file name and other numbers are ignored. If you are using the first number to count sequentially then it won't be a problem.