Ive seen that video from DF on the witcher 3, compaireing the Xbox one vs PS4 version in frame rates.
CUT SCENEs run at 30-20fps on the ps4 (by choice / design)....
INGAME both run 28-30fps and are about equally smooth. (theres doesnt seem to be more than 1-2 fps differnce while ingame playing it)
Basically the guy is blowing smoke up peoples arses :p
Here is the video:
the fps drop most noticeable on cutscenes where it doesnt matter as much.
During actual gameplay theres very little differnce in fps between the two.