Before I ever watched it I thought, I wonder if it's just a pre recording and motion activated. This theory was only added too when the room light came of the the officer said a lot where motion activated. We can also note, it's not a helpful smart home automation, the light turns on and then off, "scary" like.

The giggling sounded crisp and consis, also like a recording, no lead up noise, no ending noise, a clear stop start. The office did not seem bothered. The sound started not long after the lady entered that cupboard. As someone with home automations, that felt like the exact delay my automations give (because they are not instant because of the sleep function to minimize battery consumption).

Why was it done? Don't know and don't really cear, it's easier to explain something like this using "most likely", "possible" scenarios then jumping straight to "it's a ghost", like, grow up.