While you do have a point that language is only of communicative value if the shared terms are common, I'm just enough of a fan of Charles Taylor and his ilk to argue that communication isn't languages only function. It has deep importance for identity, if nothing else. The simple act of self-expression is significant for non-communicative reasons in that it helps us define for ourselves who we are.

That being said, I got the impression from the article that these videos are, in part, her attempt to translate her "native language" into English, rather than to talk through the use of her text-to-speech program. After all, all but the rarest of individuals thinks and expresses best in their native language.