Last short video:
The transformation aftermath got cut short in this chapter. Here's how it actually goes: Marie lands on top of the duke, the duke, looks at marie, looks down to her chest, then quickly looks up again. Then he poked marie's arm to make sure she's real. Then marie screeched, running buck naked to the door, bumping into a terrified simon, traumatizing the poor boy in the process, then she ran to hide behind the curtains.
Also note, aside from the one in vol 1, there are no manga ss short novel chapter in the rest of the volumes. I guess the one in vol 1 was put in to explain the plot hole.