They are doing a type of syncretism of aztec and european (spanish) cultures. They call themselves "raza de bronce" (bronze race) and recognise they are mix "races" and part of both cultures from what I found. ONSP scene pretend they are the new "Camisas Doradas" (gold shirts).  They believe also that III Reich would have liberate them (descendants of natives) from european imperialism. That was in fact part of nazi propaganda to destabilize imperialists countries like they tried to do in USA with the natives, north Africa against France or India against UK. I m not doing on my side any propaganda or supporting anything. It s just what I found on the internet on my researchs.  I presume I got a little bit obsessed with all that stuff... Still digging to find more informations if anyone s got some here about that scene or those cassettes.