I have an ultrawide monitor that should be able to accommodate the (what looks like ) 21:9 aspect ratio cinematics but instead of taking up the whole screen, they are letterboxed and pillarboxed. This is very jarring and should be easily fixed by re-encoding the source video without the letterboxing.
Mirrana - did you ever find a fix for this? I’m having the same problem with D4 cinematics in 3440x1440 21:9 - they don’t fill the screen like they used to before season 3. I haven’t gotten any replies so I checked my D2R cinematics - same thing, so I looked here and saw your post. Thanks.