That's something new for me then, since in both Steam and GOG release Blood.ini says that D is the mounted image and cutscenes are nowhere to be found but mentioned like that:
SourceDir=D:

CutSceneA=D:\movie\cs1.smk
CutWavA=D:\movie\cs1822m.wav
CutSceneB=D:\movie\cs2.smk
CutWavB=D:\movie\cs2822m.wav

Maybe it depends on which drive you install the game, for ex. Death Wish dosbox files uses E drive that fixed it for me. Also Fresh Supply version of the OUWB classic installer added launcher like Sharps one with line like this but the same letters:

mount C ".."
mount C "..\cloud_saves" -t overlay
imgmount D "..\game.ins" -t iso

As for cutscenes, before new release of OUWB I used
https://www.gog.com/forum/blood_series/one_unit_whole_blood_unofficial_patch_for_gogcom_edition
to extract them.
Cutscenes might work in NBlood with :. after sharp299's patch installed but had no success on clean install.

EDIT. Ok, patch still works and fixes cutscenes in NBlood but removes cloud saves line.

Thank you very much, cutscenes work after applying the patch ! Blood.ini says now SourceDir= : .

Hey guys i'm having a problem when trying to run nblood. I followed all the steps but eduke can't find duke3d.grp :(

See if it will work better with the latest dev build from yesterday. Also use the correct port for Duke3D which is Rednukem.

https://lerppu.net/wannabethesis/

Yeah, just like the DOS version. Glad you found it.

It's funny b/c I looked in all of the other places 1st - User/...\Saved Games; My Documents; etc etc.

Then it hit me - wait, it's an old game; what about the actual game-folder?
And there they were, LOL.