This situation is more akin to Amazon building it's warehouse on UPS's land to get shipments out (for a fee of course). The prior situation would be if amazon shipped via US post to UPS, then UPS ships to destination. Ideally the fee to use UPS (Comcast) land would be less than the fee to ship the product via US post (cogent) to UPS. The reduction in transit time also factors in to the decision Netflix made.