Replying to a bit of an old post here.... I dug up an update from a long time ago that confirms some of what we knew about the 3DO files. The color depth is definitely slightly less than the PSX version, however that may not be where the 3DO videos would be of the most interest: https://www.wcnews.com/news/update/6329
"Higher color of the movies (64K colors instead.... 256), The audio is 16 bit stereo and it is in dolby surround" ....
So the WC3 3do videos are all in stereo with dolby surround encoding. IIRC (not sure about the PC version) PSX version only has stereo audio on the Intro video and everything else is mono.
If there is a way to combine the color depth of the PSX version and some of the more defined edges of the 3DO with the 3DO audio, that would probably be a more definitive version of the the videos for a potential remaster.
Now that's very interesting. I would say there would be little in the way of improvement (visually) with the increased resolution of the 3DO files - a minor bump of 20-40 pixels of width/height wouldn't make an appreciable difference to the AI routines upscale purposes - but I'd be very interested in getting my hands on a better sound mix.
You're absolutely right, @AD, that the PSX version is stereo for the intro and mono thereafter. If I could get my hands on the Dolby surround audio from the 3DO version, it would be quite a simple task to mux them into the remastered footage.