In the days of El Cid, “vos” was used in the plural and as a formal form in the singular (as in Modern French). “Usted” had not been invented yet. Luego, el uso de “vos” se popularizó demasiado (por eso se usa en muchas partes de Latinoamérica en vez del tuteo), y comenzaron a decir “vosotros” para dirigirse a varias personas*. Como el voseo ya no se podía considerar como formal, empezaron a decir “vuestra merced” como forma de respeto. La frase “vuestra merced” (Vd) se convirtió en poco tiempo a “vusted,” y luego a “usted” (Ud). The same thing happened in English - “thou” dropped out of use (note that by Grimm’s Law, a TH in English usually corresponds to a T in Latin), and we now have regional variations to show when “you” is plural — “you all,” “you lot,” “you guys,” etc.

Hola Susan. Vosotros = Ustedes (España) Vos = Tú (Principalmente Argentina) En el resto de países hispanohablantes no se utiliza vos o vosotros.

Hi Susan. I just watched the same episode too. They are using a combination of "vos" and "vosotros". :)

It’s true that today’s Spanish and Portuguese speakers would be able to travel backwards in time a thousand years and still manage to communicate with little problem, although their pronunciation would be rather exotic sounding to the “contemporaries.” This is in contrast to English, which a thousand years ago was just another Netherlands dialect. Going back five or six centuries, English is already getting difficult for today’s speakers — not so bad in the formal register (think King James Bible), but could be challenging in colloquial register (Shakespeare). Actually, I’m not sure how well an American would do in a present-day London Pub…. Spanish half a millennium ago would present relatively few problems compared to English. This is not just theoretical — Judeo-Spanish from the time of Ferdinand and Isabel is still spoken, as you can hear on various Youtube videos. (There are a few Hebrew / Aramaic expressions, but mostly it’s just late medieval Spanish). One very typical Judeo feature is the lack of distinction between R and RR. Also, NUE is pronounced MUE. There’s some good music, but to really hear the language, here’s an interview with an elderly lady: https://www.youtube.com/watch?v=6q323m0RRPU

I just saw your comment. I honestly don't think it was used in the past, but they use tu as well in Spain and the conjugation ends in -s so maybe that's what you heard. like " que haces?" " de que hablas?"....