Transcribing subtitles and diffusing is exactly like transcribing lyrics and diffusing them: making a derivative work and spreading it without permission infringes on the copyright of the song/movie the transcription was based on.
If it’s considered a crime or an offence depends on the scale and context of the infringement and probably on the country that you’re in.
A subtitle file is pretty useless without a video file or disc. Transcribed lyrics, however, can be enjoyed on their own, without having access to the music.
If it’s considered a crime or an offence depends on the scale and context of the infringement and probably on the country that you’re in.