[Stuke1976]

Here is the link from Reddit I used for my Youtube video with part of the content pasted below.

Reddit CNE EX Link

Each summer Toronto hosts the Canadian National Exposition (CNE). 1969 was the first year of the Montreal Expos MLB Team. As part of that celebration the Exhibit Supply Company of Chicago offered selected baseball cards at the "National" from their 1947-1966 Series of baseball cards. Since these cards included "Printed in the U.S.A." on the front, an agreement was reached with CNE officials to stamp a special identification on the back of the cards to distinguish these as cards produced to honor Canada's entry into Major League Baseball.

No records have been made available as to which player's cards were produced, nor the volume of each card. What is known is that only a few of the stars of baseball were made available from the 1947-1966 Series. What is also known is that the volume is very small because a controversy arose shortly after the opening of the Exposition, sales were halted, and the inventory of cards was quarantined.

What happened to them is unknown and as such, pricing guides do not list these cards because, so little is known. I have discovered only three of these from U.S. Dealers over the past 27 years, and have purchased the balance of my collection of 17 cards from Canadian sources. It makes these cards Super RARE! The identification on the card back is "CNE" plus "Ex". I'm told that stands for Canadian National Exposition (CNE) plus the Ex honors the Montreal Expos Baseball Franchise.

He also reached out to another expert that he knew who replied with the following:

Yes, I know about them. Have had them for years. Only 8 were ever available as far as I know. They are Aaron, Berra batting, Cash, Clemente, Kaline with two bats, Mantle Full batting pose, Maris and Mays portrait with SF. I got the same story back then about the 69 Expo you quoted below. As for if these are legit or not. I never figured that out. You don't see that many that's for sure.

I have been told not to bother sending them to PSA as they won't grade variations or cards not in the catalogue....however Beckett might.