Well the demonstration uses Skyrim[1] to live-edit the character model which goes beyond the capabilities of a generic mod. Character customizations are also usually premium feature with free-to-play games.
Also, the technical overview describes that the rendering calls are intercepted by matching the "vert/prim count"[2] which is an interesting approach.
Vert/prim count was the easiest way to do it. It doesn't require me to checksum vertex buffers or anything like that. I'm hoping to add texture checksums as a secondary key, so that you can get some control over instancing (just modify your character's head, for instance).