Extract subtitles from movie
Solution 1:
If your video happens to be in mp4 format then for example MP4Box can be used to demux (extract) the different types of streams (video, audio, subtitles) from it. This works only if subtitles are not actually "burned" on the video image (easy test - can you turn them off in your player? If yes then all should be well).
Solution 2:
If you have the command line ffmpeg installed you can use:
ffmpeg -hide_banner -i Movie.mkv -map 0:s:0 subs.srt
Mapping depends on the subtitle track you want. if its the second one then use:
-map 0:s:1
Works with mp4 too.