The subtitles are transcription of art made by other people. As a contrast, you shouldn't borrow books from a library and read them aloud and record it and start distributing your "self made" audio books on your website.
(Granted, that the "phonorecord" must be in a "specialized format exclusively for use by blind" is fuzzy.)
“authorized entity” means a nonprofit organization or a governmental agency that has a primary mission to provide specialized services relating to training, education, or adaptive reading or information access needs of blind or other persons with disabilities;
The owners would have plausible deniability I feel, they don't know whether their users are deaf. Then it would be down to the copyright owners to address whether individual users had rights to format-shift audio tracks [they purchased] in to a format they could consume [specific language subtitles].