It's her neighbour's. My understanding is that there is thin walls, and makes recording content hard.
I mean based on the video she's wearing them in, that's not true, lol. Wedging your pants into a wet orifice tends to create wetness, which is what happened near the end of that video. The wetness wasn't there for the majority of the video. I have no idea why she didn't edit that out if she thought it was a problem, you even see her looking shocked. She only had to edit a few seconds before, which she does in a big jump cut right after.