If I posted something wrong, would you care to elaborate? Wouldn't want to continue down a path if I'm basing it off wrong information.
Things like alpha resolution buffers, texture filtering, anti-aliasing get supersampled when rendering these videos. That's why there's no aliasing, textures look good at low angles and long distances, and shadows don't flicker or show much stepping (although it's visible in all trailers posted because the blending technique to do volume remains the same).
Assets, like texture quality, models (car and environment) remain the same.
People scream at IQ "downgrades" (the sampling bit) when they slap "actual gameplay!" over (that is, direct-feed capture of "real-time" rendering, which pre-renders are not), which trailers rarely do since they are showcasing its assets with planned camera work and scenes.
And in the cases they do, it's usually understood that it was running on a different environment like high end computers or dev machines. Cases where they put "actual gameplay" over
pre-rendered stuff are rarer (PS3 CG games haha), but then they are usually backtracked as "target renders" of "actual gameplay".
There are assets "downgrades" definetely. Lower density, less particles, less light sources, lower texture resolutions. That's where all the Ubisoft games shown here shine. But again, it's understood as running on a different environment like high end computers or dev machines, and in their cases, they have to attain a level of multiplatform parity too and of course, performance throughout. You can even unlock some stuff by editing ini's with Watch_Dogs.
When it comes to GT
trailers, IQ is higher but assets aren't. That's why they are
similar.
IQ downgrades from pre-rendered videos are understood, just like increase of IQ in replays (or showroom like GT5 and 6) are too (and those are real-time renderings).
What I see is some people that are posting fact or identifying misinformation with known information and then there are some other people that are posting speculation or outright falsehoods in lieu of fact.
What I see are people getting hung up on someone saying
they are sure about something because there's nothing else to do.
And
caring about facts is a patternless tide here.