Agree with the all the comments above, these appear to be internal naming conventions specific to their workflow/game. Sorry mate even with the video you have shown it looks like you would be stabbing in the dark until you get the right combination - for example when you look at the eye it has an outside normal map and _NG looks like the base normal map so some kind of layering going on here. The _S looks like a Specular map, _P could be some kind of Position map but I'm unfamiliar with this, _SSS probably Sub Surface, _O Opacity, If i was to take a guess I would say _BS and extensions with two letters could be packed textures - for example Bump/Specular and would need to be separated by channel, or something else entirely. I would advise contacting the seller and clarify these textures and if you are using this for commercial purposes qualify that this is a legal model to use.