Videos can have subtitles / captions associated with them...
Users can enable or disable subtitles via the Game Options Menu.
File locations
Subtitles / captions are stored in the "sequenceaudio" folder:
resources
data
base
sequenceaudio
*.txt
*.txa
cam1
*.txt
*.txa
cam2
*.txt
*.txa
cam3
*.txt
*.txa
They are stored here so that the subtitles / captions can be displayed even if the videos (in sequences) aren't installed.