Waltorious: Audio and/or Video Skips / Stutters in Opening Cinematic: Often just a minor skip, but actually means that some frames are being dropped in the cinematic and the sound gets out of sync.
[EDIT: This may have been fixed with the newer v2.0 download from GOG]
1) Back up the file binkw32.dll contained in your Witcher folder, and then replace it with the one found
here.
[EDITED April 18, 2019 with a new download link]
This is still a problem in the newest version of Witcher Enhanced Edition. Maybe it is just isolated to newer hardware.
I had to also use V-Sync because for me, the binkw32.dll only fixed the audio stuttering but the cutscene video was fixed by turning V-Sync on and I have to keep playing the game with V-Sync on.
There is also a occasional lag problem that I have faced when playing on a GTX 1080 paired with a Ryzen 5 2400G.
That is the only hardware I play the game on.
The way that I fixed the occasional lag was using the Steam version. I already had the Steam version of the Witcher and I downloaded it, replaced the .exe file from the Steam version with GOG's version and it seemed to have solved the lag issues.
Maybe this will help those who have this issue and thank you for this sticky. Really helps.