Reasons for Checkerboard Patterns with S-Video
Reason 1: Your Cable is Rubbish
By flamedrake
In regards to the discussion in the Sandcastle on weird checkerboarding patterns in S-Video, I made a couple comparison shots. Here's a shot from my terrible cable with connectors for PS2/3, Xbox 360 and Wii:
Here's another screenshot taken exactly the same way except using the PS-only S-Video cable:
Multisystem cables are awful and I shouldn't have been coaxed into buying one.
Reason 2: You have Composite Video Plugged In at the Same Time
By AccountingNightmare
I had this kinda problem. Make sure you don't have composite and s-video plugged into your capture card at the same time. That fixed it for me. That might be all that's wrong.