Netflix doesn't pay an ISP. That's the whole point of the arrangement, it goes straight from Netflix to Comcast. There is no middleman. So their peering arrangement is the equivalent of "paying their ISP".
To say that Netflix should not have to pay for internet traffic is ludicrous. I want a piece of that. Comcast should hook up their network to my servers so that my personal website is fast for Comcast users. For free of course.