does the PC version use this tech?
Definitely not. I think it's something for future games (I hope anyway).
Grass can look really good and very thick in FC4 but when you get close to the ground and look down at a single patch, it's not as dense as that video! Noway.
Sometimes you can see small patches like how Skyrim does it too, not very nice.
Usually it looks great though, and lovely colours. Especially while moving, no issues and very thick in most hills.