I have this issue with Wing Commander IV running in Windows 11: the movie volume is very, very low, while the game audio is loud. I have to play the game continuously changing the volume; There is some workaround to make the videos run with a louder volume?

With the K-lite codec pack there's a tool that allows to tune the volume of each audio/video codec individually. I can't remember exactly which one was used in WC4 (but that can be verified by looking at the game files) but that solved the issue for me at the time.

Thank you. Simply installing K-Lite Standard, automatically resolved my issue.