Through some hex-editing I've at least learned that the Clip Art collection seems to be in some version of Adobe Illustrator (hence my installing CS2 to attempt to force-feed it those files), and the sounds are allegedly uncompressed, but I'm unable to get anything to load even with that knowledge. I think these are in container formats that the CD Browser would know how to work with. If only the Browser didn't crash all the time.
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
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.
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.