As it stands now, video production requires very little of a video card. Open GL is in a bad place right now and even the most demanding programs, such as After Effects CS3, can run great on the most basic video card offered. Our big issue is processor power and RAM, which are both headed in the right direction. With some exceptions, you would be hard-pressed to walk into a video or audio post production facility and not find a room full of MacPros.
Not to dampen your towel too much, but most users of the Mac Pro should know a fair amount about frame rates - especially if they are video editors. Processing video effects in real time such as in Final Cut Studio 2 would require more GPU power; not to mention that processing HD video require a fair amount of power as well. I believe editors would also want to be on the same page as the gamers for the power of the video cards that are shipped with the unit. However, the main complaint is about the iMac's video card and why they have skimped on the card - which was done for heat dispersement reasons. But in terms of getting a Pro the base line should run a game at smoothly enough, but at a higher cost. It is a shame that Apple has not considered much for gamers, but I feel in due time Apple will make the attempt to lure gamers into their realm - which should be when games can play natively in OS X, or whatever future Apple OS lays ahead.