Can't be
First off, it's a free download, but the link only downloads a readme file (???). Second, knowing a little about the os x frameworks, how would you handle things like focus? Which is the frontmost window? Seems like without majorly revamping the way the system handles user events this is not possible. You'd have to rewrite the window controller. Also, that video looks too good to be not tampered-with. How would you be able to draw in the same Photoshop window with two different colors? To my knowledge, Photoshop has no "Secondary mouse color" choosers. At best, it seems that each individual window would be able to handle input from only one, if you could even get it to handle the dual input on separate windows within the same app, which I doubt. I think all existing apps would have to be rewritten to handle this, even if only a slight revision. And finally, it seems that we would have heard of such a product already. It would be pretty remarkable.
Anyway, that's just what I think. And, yes, you can laugh at me for being wrong when this software makes it's final release and blows away everybody with it's innovative reconstruction of system events. Then of course Apple will buy them out and it will be a headlining feature of OS X.6 Ocelot. 🙂