Okay, I see it now; it looks pretty subtle in the screenshot, but it’s there. It definitely could be from crappy component cables.
Unfortunately, a lot of TRS to 2x RCA adapters are referred to as splitters, even though they’re not, because they look like mono splitters.
As for his settings, the screenshots look correct to me, so he’s definitely got both ends set to YPbPr. If the PS2 was set to RGB, he’d get no image, because the system menus are in 480i/576i, so RGBS, and both the cable and AV2 don’t support external sync; and, if AV2 was set to RGsB and the PS2 set to YPbPr, the image would be almost entirely green, because almost all the image data with YPbPr would be fed to the Green line.