Hi!
This was done intentionally to avoid unnecessary bloat, since HotA doesn't actually use any of the removed cutscenes. Could you clarify what exactly you were trying to do?
- Were you trying to run Complete Edition from the same folder as HotA?
- Were you trying to play custom campaigns/create your own?
In the former scenario, while it is technically possible to play both versions form the same folder, this isn't how GOG Galaxy is designed to work. I advise installing Complete Edition in a separate folder, otherwise you won't have access to GOG Galaxy features for that version of the game (e.g. cloud saves, playtime tracking, updates, etc.).
The latter scenario is currently too niche to justify forcing all players to download extra 600 MB of data. However, this may change if enough players show interest in this. Furthermore, the cutscenes will definitely be re-introduced in the future, once the original campaigns are fully integrated in HotA.
Either way, you can resolve this manually simply by copying the full VIDEO.VID file from any installation of Complete Edition to your HotA folder.
Hope this helps.