Well as some of us know (who actual read some reviews) some of them said that GT5 AI is not that good, well is that right ?
The video has been shown on several media outlets, that considered it a reliable source without making an effort to check (even reliable enough to include it in their reviews).
Turns out that the video is a quite elaborate ruse to show Gran Turismo 5 in a much worse light than it deserves. This video demonstrates exactly that.
NOTE: in all the clips shown in this video the player's car has been positioned on the racing line, that the AI loosely follows in normal conditions, in order to maximise it's potential as an obstacle.