[fritsch]

I have applied the recommended settings "While watching a SD(!) video, that is accelerated by VAAPI, e.g. mpeg-2 or h264" ok but do I concern myself with the settings when watching HD material as these are different when checked?

Hehe - yeah. You enabled "Use HQ scaling when scaling above 20%". That means: There won't be any HQ scalers when watching content > 1280 x 720 on a 1920x1080 Display. Those are automatically disabled then. Therefore you need to watch a 1280x720 file to be able to choose those settings. Got it?

Edit: All fine with what you did.