Mostly, movies and videos come with a separate subtitle files with a .srt or another file extension. Although most of them work automatically but some of them don't! You have to manually load such subs. And some of them don't work at all... b'coz the file is corrupt!
I will merge your subtitle and video file to make the subs permanent no matter the subs are fine or corrupt. I can also create English subtitles for short videos upto 3 or 4 mins.