CLOSTELLUMOSTIUM is the fifth video on the Aperi Oculos channel, and is the first video uploaded by someone other than the Protagonist. It was uploaded on January 16th, 2017.
(Video opens on a heavily distorted view of stone rushing past the camera.)
(Cut to a view of a mineshaft. View turns around to reveal the inside of the Protagonist's house, with the word "HELLO." written over the back wall. The "HELLO." quickly switches to "OCULOS." as the distortion increases.)
(Cut to a heavily cropped view of someone running through a corridor while looking downwards. Distortion grows. An image of the Protagonist staring at the sign from Herobrine Update #01 appears, heavily shaking, along with the words "I AM WATCHING". Image disappears to reveal the text "ALWAYS".)
(Cut to a black-and-white video showing the camera slowly passing through reeds.)
(Cut to the view of a sunset. The words "AS THE WORLD GETS DARKER" slowly appear as distortion grows. Video suddenly switches to a deep red hue, and the text turns black.)
(Cut to a shot of the mysterious uploader walking into the Protagonist's home. The words "REMEMBER TO LOCK YOUR DOORS" are placed above the door. The camera travels through the home and into a storage room.)
- The video's title roughly translates to "LOCK DOOR".
- This is the first video that was uploaded by someone other than the Protagonist.
- The music used is, unlike most other songs, completely unidentifiable.