After I watch the preview PV above, I have some guesses here.......
The part where Haruna's head get chopped was in the artifical world :
_I think i understand why Maeda screamed at the end of PV, not other members. I think because she's the last one who survive in this game so she can realize the terrified truth and feel the pain, all of other memembers are dead (I guess so)
_I also think the part where Haruna's head get chopped was in the artifical world, so the whole PV will be in the game, AKB48's members characters will be killed in the game without blood, but at the end of the PV, when they show Meada's hand is chopped off same as in the game, the audience will reallize the terried truth of this horror game