The article did leave me wondering about one thing - Mixtec is one of those "languages" that is really a giant language family, filled with mutually unintelligble varieties misleadingly called "dialects." It's the classic dialect continuum problem, though - there's no answer for where to draw the line for where one dialect stops and another starts. Oh, instead of plagiarizing from my grammar of Chalcatongo Mixtec, I'll just quote:
Ravicz (1965:40) proposes one interesting way to measure dialect boundaries in the area, días de distancia ('days of distance'): "... A person who is two days' walk from their town can communicate easily; however, a distance of three days will hinder understanding to a certain extent. If this person is four or five days from their town, they can hardly depend on sufficient common elements to establish communication, and Spanish will serve them better" [my translation].
So, having said all that, I wonder what dialect of Mixtec they use on la Hora Mixteca? Are the listeners in the Fresno area from the same dialect area, so that they can just use one and be understood by everybody? Or is a sort of standard developing that many can understand, even if it's not their native dialect?
Will keep you posted if I find out any answers.