Try luring Viktor near the end of the dead-end corridor with the alarm clock and have at least one long-lasting stamina-restoring item with you. When you think Viktor is close enough near the dead end, immediately dash to the black key shortcut door (the door next to the single locker with Albert's head, Make sure you have the black key artifact and the RUST belt artifact to save it in because it's so time consuming and so frustrating to try obtaining it again) and only consume your stamina item when the stamina bar is almost depleted. When you open that door, there will be a left and right door, head for the right door to immediately warp back to the start of the level. I will post a comment on your video later to elaborate your missing item locations.