Confusing MASKPOL Filters GOST/NATO ETC

A video hopefully explaining/demonstrating some of the confusion regarding MASKPOL filters, I had been asked to do this ages ago but only just got around to it.
The easy filters are the late model FP-5 and FP-6 filters marked as NATO as they are NATO 40mm. The FP-211 filters and P-5 filters marked as RD 40 x 4 (GOST) which are GOST, and then the super confusing early FP-5 series where every filter is listed as NATO, but some are evidently GOST threaded as shown in this video.

TLDR if you want a GOST filter probably best to buy a modern Russian DOT or BRIZ 40mm filter.