I like to think the game manages decent sized scenes and medium amount of explicitly managed bodies, and multiple octrees all active at once.
The characters are just two spheres vertically distanced at what ever the spheres radius is. I move them all around with a derived version of the character controller that came with the sample.
In the whole implementation, i never invoked "Apply" anything. Not "ApplyForce" or what ever other "apply" methods. Maybe that was wrong. Ha. It works great.
An interesting thing, is that i actually did max out on "geometry" that physics engine had to process and scaled back. But, when the whole game engine is running, which is a lot more than physics, it's hard to put blame on any one thing.
The biggest hit was the animation processing which was 100% rendering engine and 0% physics. I didn't implement physics geometry for multiple bones in a model. I had an approximation of the shape surrounding mostly, and just moved that in synch with the root bone of an animated model. I kept it simple.
SO blah. There's the video.
PGlynn also helped me in the forums while making this game, so thanks, and Jwatte's sweep and prune collision system is what makes the physics engine usable in a practical scope.