Jorpho... yes I agree actually. Should have been more specific. The game terminated after a language selection screen with a DOS message that said something like "ASSERTION FAILED:" and then listed a video file from the CD (which was the first video scene in the game). Then crashed back to dos, occaionally a fatal error depending on what CD-tricking software I was using.
In any case... SHSUCDHD solved the problem! Thanks idspispopd! Wow... I'd never heard of this utility before! ISO's as CD-ROMs in DOS... wow, what possibilities!!! Plus an unloadable CD-Driver. Just excellent!!! 😊
Anyway, yeah redbook was brought up. Fortunately this version of Dragon's Lair doesn't use Redbook (all the video and audio is contained in files in some weird 1993 codec -didn't investigate more than that).
I got the whole game to run with a fairly long bat file and the shsucdhd utilities within a menu system. If anyone is interested I'll post the bat file here.
Oddly enough, the shsucdhd program seems to affect my Ultimarc I-PAC hardware. Talk about obscure, but occasionally when I run it it cuts off my external pass-through keyboard (but not my arcade controls), and I have to cold boot to get my keyboard back. I expect this might only be useful to pretty much nobody but me, but I thought I'd report that here.
Anyway, happy happy to have Dragons Lair running on my arcade cabinet now. Thanks for the help and suggestions!
(Musing:) Hopefully I can try to keep myself from adding a ton of Turbo and Neo CDs to my emulator system, now that there seems a way to do it without an actual CD. Sheesh, probably Redbook won't work on them and that would be a shame, still... tempting!