I can't really see any coherency in your post, but then again I didn't peruse the thread. Of course they talk to each other. Also, before they weren't sharing offices in Norway. Most of AoC were already in Montreal. They're sharing offices now. That video was made how long ago? It's supposed ot show off the capabilities of the engine, not the resources used by it. Making the engine is one task, reworking resources is another.
Am I missing something, or do you actually say that it would be bad if they reuse the grass? Or are we getting into a metadiscussion about grass in AoC is not the same as grass in AO?