I believe we solved this over on Discord. For anyone else looking for a solution, make sure you install the patches in the correct order. There's a few different steps where it could break.
1. Install the game - Most likely this will only be an issue with the GOG version anyway as if you install off the CDs you can just leave disk one in the CD drive and not worry about it
2. Unzip the WCP Enhancement pack patch into the WCP directory but don't actually install it
3. Copy the HD pack videos in the the 'MOVIE' subdirectory within your prophecy folder.
4. (OPTIONAL) install the Model upgrade packs.
5. Copy the updated DLL file into the Prophecy folder overwriting the one from the WEP
- The model upgrade pack might also include a version of this DLL. If you don't use that one you will definitely need to do this step. Even so, you might have better results with this one anyway and might want to use it regardless.