When you've completed the game, you can start a new playthrough with developer commentary enabled. If you haven't beaten the game, be warned that some commentary may spoil puzzle solutions.

In this chamber, you'll find a commentary node from:

Right in front of your face as you leave the elevator and enter the chamber.

[Chris Chin] Player training doesn't always stick, especially after the introduction of a big, new concept. For instance, after they'd acquired the fully powered portal device, playtesters often forgot about the fling maneuver. Since it's such an important skill, this puzzle is designed to reintroduce the idea of flinging.