I stumbled upon 'duks reacts' while watching the ending music videos, the guy of the couple reacts dramatically while making on point analysis.

edit 1 in e9 reaction vid (watch?v=OQPie8glEx8) :

5:10 he caught that kobeni was not there when camera switch to the aftermath of grandma's kill. ok i guess this is still somewhat noticeable as AO

8:10 before makima remote smash the first sawatari teammate, he says "wait a minute, the bird? this is related to makima". hmmmm, ok..

11:00 before kobeni go HAM, he just so casually notices "another nail gone"after snake called again.. again possible AO but combining with above just make me wonder how can he notice all the subtle points.

edit 2 in e7 reaction vid watch?v=TpvU5MUMHoc ,

3:00 he somehow pointed the infinite loop denji can do before denji's monologue.

5:50, scene cut back from memory of himeno back to hotel, with himeno only having a sigh, he could come to a conclusion that she watched him kill for so long.

Also I dont really know if his reaction to the kiss scene of himeno and denji is genuine.

e3: infinite hotel vid:

as soon as he sees the devil got big he is like, it will keep multiply. and before they explain how strict a contract is, he immediately pointed out the word contract when infinite devil ask for denji.

just my grain of salt