Sup, aestetix?

I just got back from visiting family Chile less than a month ago. It's completely factual based on my experience that teenagers (Who happened to be the people down there that I spoke the most spanish with) and advertising that tries too hard to be edgy or whatever use voseo from Santiago to Puerto Varas (Didn't head anywhere further north than that but I'd guess it's about the same, not like the demographics and culture change all that much across latitude, do they?)

Actually, "vosotros" can be pretty accurately approximated to "ya'll" in english. They use it a lot in Argentina and a bit in other south american countries (Typically, amoung youth who don't really buy into this whole formality crap between each other), but it's definitely not exclusive to Spain. It doesn't carry such heavy hick-ish connotation, however, but they have their own weird set of formalities in that language that can be approximated to English equivalents. Think if English still used "thou" and "you" in addition to "ya", and you have in spanish "usted" and "tu", in addition to "vos".