I have to say, watching the video i hadn't realised the extent to which chroma key filming was being used - but i'm not surprised it's being used.
The famous T Rex chase scene in Jurassic Park was made using a mass of Amiga 4000's with Video Toasters working in collaboration with another host of the most powerful PC's at the time.
The same scene can today be created using my iMac or similarly specced Windows based PC - or for those with a bit more money - A Sun Workstation.
It is that evolution of technology that has made things so cheap to produce. Even i've done some portrait stuff using chroma background and then overlaying in CS4.
It is no longer the preserve of the wealthy or the technically gifted spotty oik.
The phrase "the stars do their own stunts" doesn't have the same ring as it used to. Must also save a fortune in stuntmen, insurance, and H&S jobsworths.
It'll not be long before they are able to do away with body doubles.