c_major,
Yes, still having issue with dark portions of videos. My current project uses clips from Star Wars. This effect is really noticeable in Vader's suit. I'm not sure on the codec. I haven't changed anything, so whatever VP uses, I guess?
I usually export to .mp4 but I just tested exporting to .avi and same thing. I also have played it with different players.
Here's a video I uploaded to YouTube to illustrate it. I took the first 10 seconds of the famous Bark Side video and faded out the last 3 seconds. You might have to put YouTube on full screen to see the effect. After it fades out, you can still see portions of the screen that aren't black but gray and blotchy. It seems that how much this happens is variable. I have gotten smooth blacks before, but I have to export over and over. My most recent project i finally faded out to white and then to black and it worked fine (but maybe I got lucky)?
[Unneeded Video deleted]
eta:
Here's another video I made that shows it even better. I put a blank black clip in the middle of 2 short videos and you can see the artifacts all up and down both sides and along the bottom of the screen.
[Unneeded Video deleted]
If I didn't point out, it looks correct when I preview it in VP. This just shows up after exporting.