Expand that hypothetical a bit more, so that we can determine if the situation you're asking about is one that ever happens in the real world. Are you asking about traffic imbalances at peering points? If so, the agreements in those cases are between ISPs and do not include end users like Netflix as a party to the negotiations or payments. The primary purpose of an ISP is to ensure that their subscribers don't have to worry about whose lines their packets might travel on to get to their destination.