There's another ios accessibility setting that inverts video on the whole screen, which is surprisingly good for dark settings. I don't want the blinding white background to be dimmer, I want it not to use a white background in the first place.
iOS 9 auto-brightness mode goes a lot dimmer than its predecessors.
Is this the case even with older iPhones? Haven't really noticed it myself, but haven't been paying attention, TBH.