Slower teams don’t need to start from the pitlane to make changes. They already know they are starting last, so they do their best to set the car up as good as possible.
Red Bull doesn’t. They try to set the car up to be on pole and control the race there. It’s a massive difference in terms of setup if you start on pole than in the middle of the pack. The difference is where they are supposed to qualify.
Adrian Newey said (in that clip where he’s driving the Leyton House and the RB6) that their simulations tell them that the fastest laptime is achieved with maximum downforce and not su much top speed. So they do it that way, to ensure a good place in qualifying. That’s why Webber often struggles to overtake everyone else, cuz he’s often behind Vettel, and he gets in the mix with other cars and get stuck. Surely that’d had happened to Vettel had they not changed their gear ratios and downforce levels.
What it is interesting is how fast he was on race day. This car isn’t as good as the RB7 in terms of qualy pace compared to the others, so they must be scratching their heads about what to do now, now they know their car is very competitive on sundays with the longer gear ratios and the different downforce settings. Surely they can’t risk it and aim for pole no matter what, and if they miss, the get stuck behind others.