As the pot is adjusted higher on one side, the resistance will decrease an equal amount on the other side.
In this arrangement, the potentiometer acts as two resistors, one for each side. The circuit behaves as two series circuits.
1. What happens when you turn the pot all the way to one side?
2. What is the total resistance of the circuit on the side with the LED light up?
3. What is the total resistance of the side with the LED off?
4. Why does each LED have a 220Ω?