It is actually pretty good demonstration of what one can do with CGI. Artists could pull off more stuff like this to show what imagination can do. Please take a look further in video where the author shows it to be computer generated instead of real by providing some impossible constructs.
The reason why it seems so realistic is probably because video seems to use photographed textures. However, wooden surfaces didn't look real in the video, also there are some problems with the contrast in simulated direct sun light. Overcast weather provides quite realistic looking images.
Modern simulation capabilities are amazing.
