At 12:26 the BIOS of the Origin PC shows that it has an i3-8100 instead of the i5-8400 that the rest of the video talks about, what's going on?
Edit: Never mind, spoke too soon. This is explained at 20:30
If it's a canon camera the aperture should stay the same if you detach the lens while the camera is on. If it's a Nikon you'll have to hold the spring loaded aperture control "tab"