"when did peach die?"
Mario.exe explains. in the level 1-3, mario stops past the flag, and a jumpscare starts with text displayed, "Look back." after going back you see mario, your brother, with red eyes, mario.exe himself, holding peach over the edge. then you see her run down the wall and die of "fall damage."
the video capture of it is NOT BY ME, and I didn't watch it because I already saw it and IT. WAS. CrEePy.