Video editing actually does not task video card heavily, as long as it's not *D work as already mentioned above. Any modern low-mid range gaming card will work fine for video editing. I tend to lean towards nvidia for Photoshop work. Video editing work is highly dependent on your processor- you want a fast quad at least, 8gig of memory, or even maybe *6 since its not expensive anymore.
A fast hard drive is also a big plus. An SSD will amaze you if you can budget it in.