update: the programs work, the files i was trying to open do not.
https://archive.org/details/3DO-Content-Library
this collection of 100-some CDs (and a further 140 not yet dumped, apparently?!) is what i was targeting - the discs are meant for a Macintosh (since that's what the 3DO development toolkit ran on!), but beyond getting the CD Browser and Text Index to start (and then crash when I search for anything!), I can't figure out how to browse it at all.
The trickiest part of the whole thing is, since this entire thing is from 1993-1994, it targets Mac OS 7.x, on a hardware generation that I don't have. My oldest color Mac is my G3 that only goes back to 8.6, and my only 7.x-running Mac is my Plus which probably isn't strong enough to run the browser, let alone mount the CDs.
I did manage to get 7.6 installed to a Basilisk II instance, but nope, stuff still crashes in that... Probably need a real-steel Quadra or Performa here.
By all of that, I can make an informed assumption about what the 3DO Content Library really is: a ready-made compilation of existing libraries of assets, images, sounds, music, and video clips, provided by the 3DO Company to its licensed developers. Perhaps its container formats are specifically formats already meant for use with the 3DO hardware, to remove the need for conversion?
Such a collection existing would certainly explain a lot about some 3DO games' aesthetics. Videos and all.
I can at least glean some things from reading the other files on the CD Browser disc; there's an Excel spreadsheet on there with the names, addresses, and phone numbers of all contributors to the Content Library. This includes dozens of photographers, a well-known clip-art library, Sound Ideas (best known for producing the sound library used in Doom), and multiple stock video libraries, including Prelinger.
I would assume, the same Prelinger as this one: https://archive.org/details/prelinger?tab=about