I have this problem also.

The GoG version has ScummVM 2.0.0 from December 2017. You can download 2.2.0 from scummvm.org and extract/copy over the version in the Zork folder. If you verify / reinstall thru Galaxy, then it will be overwritten with the 2.0 GoG provided version again.

I was pleased to find that version 2.3.0 (as of now not released but available on the ScummVM as the daily build) allowed me to play the high quality DVD movies for ZGI. You just install ScummVM anywhere (like the default install directory) and then run it. Then add ZGI and point to the GOG install folder for ZGI. Presto!

Indeed. That is what I do. But many people expect, sometimes, too much from GoG. They do what they can. but Microsoft updates windows 10 a lot that breaks things once more. And GoG has so many games they try to make sure it is compatible. But when the "most compatible" OS ever breaks things often, and you have 1000's of games, not an easy thing to keep up with. And so many people think the developers are here monitoring these forums. Most are not. Most are not even active, or neven exist as a company since... 80's or 90's. Privilege. Leave it at that.