If you are playing the DVD Version of WC4 (GOG-Release) you can and should use HCIs patch:
https://www.wcnews.com/wcpedia/GOG_WC4_Video_Patch

If you are having problems with video playback of the movie upgrade pack (https://www.wcnews.com/chatzone/threads/ive-created-a-wc4-hd-video-pack.30415/) you can try to change the VideoRenderer from vmr7 to evr or ivideowindow.

Since those (possible) options are only found in the source code of the patch, maybe someone will find this listing useful ;)

Renderer.cfg:
opengl (default)
ddraw
direct3d
legacy

VideoRenderer.cfg:
vmr7
ivideowindow
vmr7offscreen (default)
evr

audioRenderer.cfg
dsound (default)
waveout


Enjoy :)

Thanks or sharing all of this. That said, I was able to get everything working fine with the exception of the cinematics being stretched on my widescreen monitor. The best videorenderer.cfg setting that sort of fixed it was evr, but even that left it a little stretched to the extent that some scenes cut off the top of the heads of the actors. It also caused videos to freeze after each clip and you had to press esc to get the game to advance. Apparently this is a known issue and there isn't a solution available that I've been able to find online yet.

I finally decided that it wasn't worth playing the DVD version of the game at this time until some solutions can be discovered so I decided to uninstall the DVD version and install the Dos version instead. Then with the dos version, I used the same tweaks receommended in these forums for WC3 AND I downloaded the wc4 dos fix.zip file discussed here:
https://www.gog.com/forum/wing_commander_series/wing_commander_iv_dosversion_error_open_failed_on_file/post1

Doing all of this fixed my dos version of WC4 and it worked perfectly. I just finished a full playthrough and it was awesome fun!

Thanks for sharing your experience with the settings.

There was more analysis and discussion here:
https://www.wcnews.com/chatzone/threads/hd-video-packs-tech-support.30834/

For me personally, the stretched video bug was solved by using ivideowindow as renderer on 4K or FullHD 16:9 displays (AMD Radeon with latest drivers / Win10 21H1). On Intel onboard IGP ivideowindow was not working, but evr was. I never experienced the freeze bug, but I know it exists.

Personally, I wouldn´t want to miss the upscaled videos anymore ;)