It can be used for synchronizing the subtitles to a movie when there is a slight offset between the two (this can be the case when the subtitles and the movie come from two different sources), or when there is a time scale difference (for instance if the movie and the subtitle file have different frame rates). The faster solution, is to use an online tool like this one offered by the guys at Bits'n'Bites that allows you to upload a SRT file and synchronize (shift) the time of the subtitles. These tools shift all the time stamps of a movie subtitle file. That's pretty useful, however the configuration will be stored in the player, so when you move the files of computer, you will see the problem with the subtitles again.
As you can see, there's an area to delay the subtitles in a specified ammount of seconds. Nobody is downloading any pirate version of the John Wick moview here. Probably, you already use a player program that includes the feature to delay the time of the subtitles, for example with Power DVD 17, you can easily do it in the subtitles option: Unfortunately, the subtitles doesn't match with the parts where the actors speak. and the movie comes in a language that i don't understand, however the quality is without a doubt the best that you can't find on the internet, so you simply decide to keep the file and search for subtitles on the internet. I can't count all the times i downloaded a film.