Yes well at least that helmet matches to the ESB movie poster so it is confirmed to be promotional although the rest of the costume doesn't match the poster costume.
I had a few more things to touch upon about what was said in the interview.
He initially referred to the company 3M as "3 millimeter".
I checked Lucite's website and there is no code 912 for color that I could find, although I did find the 504 and it looks close to the stunt mask eyes:
But he states the cheeks and neck on the stunt mask is code 912 and is a "greyish" color when it is instead a dark green.
As an aside this particular color below looks similar to the TK/Boba Fett lens color (but I don't think it is the neck color on the stunt mask):
He states that the teeth are thinner on the auction mask because of the shrinkage effect of the mold. Nonsense. The teeth are not in their original configuration and have been trimmed, leading to wider gaps. Going back to his claim about the I am your father scene mask having the same teeth as his mask. Nope. The auction mask teeth were trimmed leaving them narrower than the original and the gaps larger than the original as seen below. The bottom mask has the accurate teeth for both ANH and ESB. The auction mask teeth are simply not accurate or original and it has nothing to do with how it came out of the mold. You'll even notice that the second from the left tooth gap is just a bit wider on the 20th C ESB promo mask, and it is also the wider tooth on the screen mask and in fact the teeth and gaps are entirely identical between the ESB promo mask and the screen ESB mask, but very different from the gaps on the auction mask. So, no, it isn't a result of how it came out of the mold.
He states that Andrew Ainsworth said that with a hard mold there will be stress marks in the same place every time when it comes out of the mold. So this would be in reference to what the owner claims are stress marks on the mask that were repaired. So the owner doesn't seem to realize that Andrew is referring to the type of positive molds used to make TK helmets and that is probably why he thinks that the Vader helmets came out of hard molds. Talk about majorly confused. :wacko
He states that Don Post was given authorization to make the owner a Darth Vader costume and it turned out it was ANH like. So the question is, given authorization by whom? Lucasfilm? If Lucasfilm, they would never give someone authorization outside of a licensing agreement to do something like that.
The saga continues...