I'm not sure which part exactly, around that time mark they were strapping the cables to the back of the motherboard tray using the included velcro straps. That's part of the case and allows people to route the wires behind the motherboard and secure them in various bundles. The only other component they used was an extension 24pin cable for power to the motherboard pre-sleeved in white.
If you're referring to the inside of the case where the motherboard, cpu cooler and gpu are visible, at one point they had the case turned in the camera view and on the right side of the screen was the psu cover. That's also included with the case. Those are about the only things I can think of that were cable management related. Not all cases come with a psu cover (if that's the part you meant) and not all cases are set up to use one. They come with the case and there are a few cases which have psu covers.