Are you absolutely sure that this actually IS a Video-In? From the official ATI page I would believe that this card has only Video-Out capability, and for TV-Capture you have to add an additional card.
As stated on the ATI-page (http://ati.amd.com/companyinfo/press/1997/4072.html):
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Tri-View, first for triple-screen
viewing With competing solutions offering support for only two displays, the 3D RAGE LT PRO, with Tri-View architecture, is the first mobile graphics chip to permit triple display of simultaneous outputs to TV, CRT and LCD. Different or same images with different or same resolutions and refresh rates can be viewed on any two of the three displays. This feature is useful for financial applications where a user can span an image over 2 displays for a wider viewing area; for CAD design where a zoomed-in image can be viewed on one display and a global view on a bigger one and for education or business presentations to allow users to display a preview image or notes on the notebook screen, for example, while showing a different image on a CRT or a large screen TV.
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The ultimate in connectivity with ATI's AMC and Zoom Video Port
The ATI Multimedia Channel (AMC), a 16-bit, bi-directional video port allows direct connection to popular video upgrades, such as video capture cards, video conferencing hardware, hardware MPEG-2/DVD players and TV tuners with Intercast support. A Zoom Video Port with maximum support of 40MHz, and 16bpp YUV422 is also provided through the AMC bus.
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