I recently asked Twitter, are these cards?
Computer-driven graphics hadn't taken over sports coverage in the 1970s and 80s, so TV producers leaned on still photos when they needed an inset or single-player highlight. For example, did Weaver get tossed out once again arguing balls and strikes? (He's third all-time in ejections, with 94.) Here's a photo to flash on the screen while talking about it.
I took Earl's HOF visage from what appears to be the "team set," numbered contiguously for convenient storing and use during Baltimore broadcasts.
TV needed to cover multiple teams and sports, so Earl and his Orioles are just one of many, many slides out there. Not sure if it's possible to make a comprehensive list of what "full sets" would be, but the numbering will help someone who wants to take on that challenge.
I expect hunters of specific players are most likely to grab slides for their collections. Here's an interesting one, Pete Rose during his 1984 stint with the Expos (as of writing, it's $17 BIN).
Poll results: Twitter responses voted 10-to-1 that slides don't count as "cards," but commenters agreed they're interesting. Best wishes to those taking on the challenge!
Value: eBay sellers list single slides and team sets for $10-40 (here's an example), depending on the mix of players.
Fakes / reprints: Even for stars and HOFers, I doubt photo slides are valuable enough to spend the time and trouble faking.