Actually it's all just speculation about something that has not been confirmed yet by the developers.
As it was explained in the other thread, there were some graphical flaws that wouldn't appear it the video was indeed pre-rendered, so that almost throws that argument out of the window.
The argument of it using multiple PS3 to render, could be true, but, once again, there are some parallels between the vid and the gamescon/jeux paris gameplay videos, like the global lightning, the car reflections, the road textures and car geometry. I think if it was really using 3 ps3's to render, the final quality would be better.
Once again, this is just my opinion, hopefully someone will read through this arguments and not just jump on this thread without reading anything.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
