The F430 was driving surprisingly slow at the time, being followed by another STI that braked in an attempt to keep its distance from the supercar.
At the other end of the corner entry speed scale, we find the blue STI mentioned above. The Subaru entered the bend sliding on the grass, with the driver clearly having carried plenty of speed into the twist.
While the STI was using the full capacity of its intelligent all-wheel-drive system to avoid spinning, the low grip meant it couldn’t pull its usual laws of physics-defying moves. As a result, the STI still carried plenty of speed when it re-entered the track, hitting the F430 from the side.
Just like in terms of road driving, one should always check the mirrors while spending time on the track. However, the Ferrari driver can’t even be accused of that, since the Subaru seems to have hit him coming from the mother of all blind spots. Judging by the trajectory of the Ferrari after the impact, it doesn’t seem like its driver instantly stepped on the brakes, so the surprise might have been a bit too much for him.
Unfortunately, the impact was pretty serious, with both cars sustaining damage that looks costly.
An explanation for this? We can say the Ferrari driver saw an STI hitting his supercar out of the blue.
Update: the footage of the crash has been removed by the Youtube uploader. Since the clip had been edited, with slow motion bits and two angles being introduced, it's obvious nobody wanted to throw away their precious time, so we can expect at least one of the involved drivers to have complained about the public video of their accident.