Should be careful using the word premium here as it's fundamentally wrong. Premium in market financialization has to do with an amount over fair value
What governs the contract value is either supply/demand vs time value. It has nothing to do with premium.
Furthermore, the current ES term structure is backwardated. So as he rolls, the value goes down, not up, in this instance.
If the difference between the futures and cash is a negative like it is now, usually (or at least used to be) referred to as "negative premium"... still maintaining the "premium" moniker by convention.
Years back when interest rates were higher, the futures traded at a premium over the cash.
(If interested, I'll introduce you to my wife. She also likes to argue minutiae)
