There's actually a third dip: Comcast can tell the customer that for an extra fee they can get faster Netflix.
That is, even though the customer is already paying for internet access, Comcast can throttle Netflix traffic (even making it unusably slow), then offer to the customer to remove the throttling ("get turbo Netflix speeds!") for an additional fee.
That is, even though the customer is already paying for internet access, Comcast can throttle Netflix traffic (even making it unusably slow), then offer to the customer to remove the throttling ("get turbo Netflix speeds!") for an additional fee.