Yes the price increase is bogus, but there's definitely physical improvements to allow the camera to output that kind of high bitrate high res video, even with 1080P on the other DSLRs they struggle with overheating, but even with quality components added for heat dissipation I don't see any of that adding beyond $1K.
Also, EOSHD reports disappointment with a test shoot using the 1DC, rather soft output similar to how the 5DMarkIII video looks, doesn't make any sense...