I think that it would sell if it was made to a high enough quality that it wouldn't be prone to leaks. The video clearly shows that there was some thought put into its design and to me it looks like a solid product. While I have no use for it - I am sure many others would.
In fact I could never use that even if I wanted to. I have prescription lenses in my masks and unless you are going to double as a custom lens maker it would need to be retro fitted on - that is not a risk I am willing to take.
The market for a gadget such as this would be relatively small as well - so that is something to consider. Chances are the already existing defog market of products will make you unable to enter the market at high volume of masks, I do see the potential to sell a small volume of them to people who find them interesting.
So your clients would probably be: People who don't need prescription lenses, People who don't like defog and other gadget people like yourself.
Your clients would not be: tech divers, dir divers, gue divers, people who enjoy putting defog on, people who want to mitigate failure points, people who think if it's different it's a gimmick.
I think that your product falls into what I like to call the "spare air category" - An interesting product that isn't useful enough to edge out the competition. You're competition being defog. Spare air gets dominated by 6cf-13cf/14cf pony bottles.
Try and sell it! I would.