Think we should really abstain from comparing displays by youtube videos
Z2 looks over-saturated, but then again it might be due to X-Reality, Bravia or simply the fact that IPS LCD have more brightness than AMOLED displays, and they say both handsets are set at 100%. Too many details that can completely change the outcome.
One thing is certain though. If it looks over-saturated, than it means that the display is capable of producing ridiculously rich colours, which in my opinion is definitely better than not being able to produce them at all - like previous Sony displays ( Z, Z1 etc )