It's a common ghost story: dude feels the presence of the dead around him, sets up a camera, and sees images of his dead girlfriend bumming around his room.
Since Newtypes can sense other Newtypes' energy (sometimes seen as ghosts), the joke is the random guy and the dead girlfriend are Amuro and Lalah, because Amuro has seen Lalah's Newtype ghost before. Yuyuko's there because she's a regular ghost and why the hell not.
And now the joke is ruined because I had to explain it.
What the? Amuro?? Lalah? Huh? So Lalah spirit didn't go to Newtype world but to Yuyuko????
She's recorded to play around outside the border (even showing up with merry and renko once)
MorichikaFirst time I've been to Rin-kun's room.Curious about it, he tries setting up a camera in his room.So, you see, isn't Rinnosuke easy to observe?...Urban legend verification?Yes, you don’t move a lot~Yes! It’s a famous story...When he gets back home and checks the images, he sees a woman in them... that sort of story!A certain young man feels he's being watched in his room for some reason.※Rinnosuke is forced by Yukari to monitor these two so they don't randomly cross the border.Being observed by the people I'm observing...