Are you stupid, or just completely ignoring what people say?
YES, the trailers are rendered. Is it not extremely obvious? Just LOOK at them. Yes, consoles can chuck out some pretty decent Graphics nowadays, but nothing like that. Like i said, it's also obvious due to the fact that alot of the trailers feature footage with EXACTLY the same cars at the EXACT same camera angle with the cars doing the EXACT same speed, only with added objects, like that plane for example. This proves there pre-rendered scenarios that they have made and created, and they have just re-opened them and fiddled with them a little bit.
And the video you posted of the Menus is gameplay yes, but just with upped Graphics and some animations from the pit crew, so i don't know why you find that impressive. Games have been doing that for years.
And just to add, stop using the demo's file size as an excuse. Just because it's 200mb in size does not mean it's "stipped down" Graphics wise. The Graphics you see while playing are pretty much what you will see in GT5. If your expecting the Graphics in the time trail demo to be drastically different to GT5's, then don't expect a release date this side of 2015.