Sounds like you missed the .fxcomposer and .fx files, which were posted along with the presentation. The video is there just for people who don't have a GPU capable of running the demo. The easiest way to view it is to install FX Composer and then double-click on the PCSS.fxcomposer file. Once it's open, you can freely manipulate the scene, add new objects, translate/rotate/scale them, change the number of samples, and change the light size using a slider. Once you start working with soft shadows and more accurate penumbras, it's hard to go back.
I would be interested to hear where you've seen or read about this technique before. All the developers I showed it to at GDC had not seen it before, and it doesn't look like it's been published previously either. Perhaps you might be confusing it with some other algorithm (there are so many!)
Regarding usability in games... shadow maps of course have two instrinsic flaws: aliasing (jaggies caused by insufficient shadow map resolution) and bias (artifacts caused by insufficient depth precision). The good news is that filtering addresses aliasing quite nicely. If you set the light size to a really small value in the demo, you'll see how little information there really is in the depth map. (The light is too far away from the scene in the file I provided. Moving it closer would make better use of the shadow map resolution.) Bias also gets blurred out, but picking the right bias value for a particular scene can be a bit of a pain.
On the other hand, shadow maps are quite robust in terms of handling alpha tested, displacement mapped, non-convex, and other geometry. In addition, GPUs are good at reading and operating on textures, so techniques like filtering for softening shadow maps are viable. Conversely, trying to get soft shadows with shadow volumes is a lot more complicated. Lengyel's recent slides from GDC do a good job of explaining that.
The main issue for an expensive technique like the one I presented is the performance impact. The whole idea of presenting it at a "Next-Gen Special Effects Showcase" session was to give developers some ideas to think about for the future -- particularly because rendering soft shadows is such a challenging and important problem. After all, if their games will ship in a few years, this technique will be relatively quite cheap by then. I also think that the technique can be valuable when modeling scenes because the soft shadows give great cues about the spatial relationships between objects.
Finally, as I mentioned before, the technique can be quite fast even on today's high-end hardware, if combined intelligently with texture masking.
Randy
