Until 1976, are you sure? This docu shows "Le Fromage de Comté" and it's dated 1927:

https://youtu.be/icu-oMerROI

One of the legends points out the similarity with Gruyére, but it still calls the French cheese Comté:

"Le fromage de Comté, analogue du Gruyére suisse, se differencie de l' Emmental..."

Well, I could be wrong. The AOC rules certainly came fully into force then. And as a kid in France <= 15, I'd buy Gruyére in the grocers, and it wouldn't have the snazzy Swiss cross printed on the rind. Perhaps until then, "Gruyére" was a generic term, and they'd sell you Gruyére or Comté, whichever they had.

It was used as a generic term. Even now, people commonly say “gruyère” when they mean “emmental”.

Right, so I guess the video is evidence that the producers of Comté were trying to establish an identity for their product, separate from Gruyère, but consumers, as usual, used brand names as product category names.

That's very common. In Greece for instance there's a PDO cheese called "kasseri" but all of northern Greece calls all hard or yellow cheeses "kasseri". Conversely, they call all white cheeses "tyri" ("cheese"), which usually (but not always) means feta, which is in turn a PDO name for a specific kind of white cheese made in certain areas of Greece only.

I guess it's the same thing with French cheeses and Italian cheeses, and every other place's cheeses. Heh.

There's been a couple of comments suggesting that emmental and gruyère are easily confused. I don't find that, with one exception.

With the help of my local cheese shop (mentioned upthread) I came across what they call "proper" emmental, which is a very mature emmental, a bit like a mature gouda. Only a bit rubbery. And silly expensive, but very nice.

French Gruyère now has AOC status as well, but it must have holes to distinguish it from the Swiss one: https://fr.wikipedia.org/wiki/Gruy%C3%A8re_fran%C3%A7ais