VIVO can either use composite or s-video it varies.
A tuner takes a signal that has several signals on it at different frequencies then when you select a channel it takes a particular band of frequency corresponding to that channel and gets a signal that is somewhat similar to a composite signal with audio thrown in.
Video out means the card can send either composite or S-video to a video device (TV, say). It's (usually) handled just like a monitor...you can clone the current view, or span the desktop across the monitor + TV. Generally you can't do TV out and Dual monitors at the same time.
Video in usually doesn't have a tuner. Like Cryect said, the signal coming from an antenna or cable feed is a whole bunch of channels mixed together. The tuner filters all the unwanted channels out, and you're left with the one you want. On a VIVO video card (again, generally) the input has to be a single channel...like the output from a VCR or video camera (if you're doing this to get video camera footage into the computer, look into IEEE-1394/Firewire/i-link/DV <stupid, isn't it...they're all the same>. The picture quality is great! With a digital camcorder, it's essentially perfect!) Hope this helped!
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