They are not talking about video cards. They are talking about video editing cards. The editing card usually has Firewire and Analog video (s-video, composite) inputs/outputs. It may also have a breakout box (you will see that also referenced as the BOB) that also includes a PAL or NTSC monitor connection. Really advanced cards (read 'expensive' as in $25000) have connections for Beta and some of the advanced video formats.
But, a video card can help. A faster card can give better results in HD display and reviewing complex effects such as multiple Picture in Picture, but that might be marginal. Pinnacle Liquid Edition and, to a much lesser degree, Studio 9 use the GPU on the video card to render some effects. Pinnacle has used Direct3D to render their GPU effects. A fast GPU can increase the speed of the background render of the effects. A fast GPU also allows for more layers to play in real-time in the editor. With my system, I can get about 10-13 layers to play in the in-editor monitor in real-time. A faster card will probably yield a bit more (waiting for Gateway to actually ship the X800 XT PE). The new ATI and nVidia cards also have MPEG4 and WMV encode/decode chips that should help with renders as the software evolves.
