I think they are hidden within game files on newer patches.
I think you need what's called a CASC viewer.Damn. Why would they do that? Any idea how to access them?
Edit: NVM, Subtitles work
Since you mentioned them, and for the sake of completeness:The audio part is in [yourlocale]-war3local.mpq\movies\audio\
..., where [yourlocale] can be: dede, enus, eses, frfr, itit, kokr, plpl, ruru, zhcn or zhtw for now.