Alright I found the correct selection in the preferences!! I even found this nice Game mode feature which will benefit me because I do intend to connect something that I want to minimize latency on.
For a test, I hooked up an old Pioneer DVD player over the S-Video input and made sure EyeTV had this input selected. For a moment, I did see a screen flash by after it powered up but then nothing. I tried a different cable also but still no picture. Then I thought of something. Will the EyeTV 250 Plus accept a progressive scan signal over S-Video? The player is currently set to that and I cannot disable it from the remote.
Maybe the 250 Plus will only work with Interlaced. Crud. That probably means I will have trouble with my game machine also.