Well, the DVD and the writing on the window were clearly meant to scare her, and presumably they were both done by Rentaro (who could have set it up when he was visiting Yumi the day before) -- but why? Yumi was already out of the ryokan, and she was actively urging Miwako to move out too. What on earth could Rentaro possibly have to gain by scaring her?

No idea, folks. Maybe it was just to help convince Miwako all the hauntings were real, but that doesn't make a lot of sense. I think probably it was just over-enthusiastic programmers who decided we'd gone too long without being spooked. Me, I prefer a plot that hangs together and makes a modicum of sense. But maybe I'm missing something here.