Found one more issue when trying to stream old game :) If capture resolution set as 800x600 (for example) and same resolution of capture, but game starts in lower resolution for play splash video or intro, OBS capture this 640x480 area just fine, but another part of captured area begins filckering. After intro game sets resolution 800x600 and flickering stopped.
I recorded VOD which show this issue. This is not fullscreen but VMWare window :)
I recorded VOD which show this issue. This is not fullscreen but VMWare window :)