ok you are the best of us.Compared to what... an aluminum squirrel cage? Sure, I can believe that aluminum is better, but it's not exceptional in any way. Both copper and aluminum are routinely used in induction motors.
I'll save other readers a couple of minutes: there's no technical information in the sales video, other than that the motor has a copper-bar rotor.
That's one antique video! It's actually shows a prototype, from before production introduction (although that doesn't matter in this case because nothing substantial has changed in the Model S since then). The on-screen caption which says "copper rotor inside" is pointing to the wrong place: it points to the inverter, not the motor. I always thought that Tesla made the inverter housing cylindrical to give the illusion of two motors (and of all motor, no electronics), and in this case it appears to have worked.