We would draw your attention to the multiple alternative media formats that are used by persons with disabilities as set forth in our W3C Note publication: "Media Accessibility User Requirements (MAUR)" available at:
Please note that this document was developed in order to inform the development of the HTML 5.0 specification itself. As a result of this note, HTML provides sufficient feature support to support accessibility in HTML's video and audio elements.
Our reading of the TV Control API draft finds no way for users to learn of the presence of any MAUR identified alternative media with any particular TV content, nor any means to request display of alternative content. This is a fundamental accessibility requirement on TV Controls and we believe it must be factored into this specification.
Feedback from the Accessible Platform Architectures (APA) Working Group at https://lists.w3.org/Archives/Public/public-tvcontrol/2017Mar/0043.html: