Wii Component Cables: Problem with VC?

This morning I got my component cables (finally) all the way from Hong Kong. They're 3rd party, not sure exactly which manufacturer.

All seemed well, Zelda was crisper than a crisp thing, until I tried some VC games. Started 'Mario Bros.' but all I got was a weird green flickery screen. Couldn't see the game at all, but I could hear it. When I press the Home button the menu appears with the gameplay shot in the background, but when I close it: back to greensville.

Any advice on how to deal with this? Is it my TV, or did I spend £15 on some really bad cables? I so don't want to pay £30+ for official ones...

EDIT: Oh, and I'm in the UK - maybe it has something to do with PAL versions?