skip to 0:33 sec to get to forza 3 cockpit,

A GT car with a closed cock-pit (non-F1 car) would have made the comparison more on par. Also maybe using a car available in both games.

I hate cockpit view. Until they can change the view based on what you are thinking, there is no easy way to look through the corner, which is what you should be doing if you are driving.

Also, I don't know how you can determine who has the better cockpit view from two totally different cars.

Maybe it could happen with GT and PSEye.

I thought about that, but if you actually turn your head you won't be looking at the screen, so it won't do you any good. They could add some code to make you look generally in the right direction with no external input, but that may get trickey if you drive eratically or go off the racing line.

Do you ever play with a steering wheel? Cockpit view is the only view you need if you use a steering wheel...

I have in the past, but I haven't had a wheel for a long time. I'm thinking of buying one cheap. I don't see how having a wheel makes cockpit view better though. The last time I used cockpit view was for F1 World Grand Prix for the N64, but then I could easily see both left and right so I could take the corners.

Basically this, and besides, playing with a steering wheel is the only way to play. The wheel adds SO much that it feels like a completely new game.

Also, a fairer comparison:

i like shadows and reflections in GT5

You chose a bad car for GT5P to compare. A closed top road car would've been better.
Anyways, from that video, F3's interior rendering isn't as detailed as GT5's. Look at the bars in the cars. Also, there's real-time self-shadows in GT5, which I don't see in that video.

PS. That F1 driver is amazing...