I see the problem!
If you look at the still of the video of the adapter, you see the 3s plug only has 3 wires- it should have 4 wires- ground and cells 1,2 and 3.
The 4s plug has 5 wires, and should only have 4 wires- the positive voltages of cells 4,5,6 and 7. Ground is shared and only necessary on the first plug for our new 8s end. The 4s plug should omit the ground wire.
Hobbyking really fudged up that adapter.