I've bought a third party Wii S-Video + Composite connection cable for my european black Wii (PAL / Wii Sports Resort + Wii Motion Plus edition). The connection of S-Video and my tv tuner card results in the following:
which transforms to:
The Wii "Screen" menu states that 480i is selected as output mode. My tv tuner card works perfectly with Xbox 360 S-video output when set as PAL 60.
Edit: I should also mention, that I've read that the european PAL Wii isn't capable of S-Video. Even though, there are (third party) adapters availabe in the european market. But the screens attached show that there is something like a S-video signal, which is more than "not capable with S-video".