Whenever someone "reaches an agreement" payola is involved.
Not necessarily. In this case, Comcast got another bauble for it's array of X1 services and Netflix probably gets closer to some metric like "Integrate to profitable platforms". If both are seen as advantageous by the respective parties, there may not have been any money that changed hands. That may be unlikely, but it is possible.
The part I find odd is that you somehow assume that, outside of providing you with the contracted service for the given price, that the companies involved have some responsibility to run their businesses without other external financial interactions. Does this extend to the other vendors Netflix deals with (like Samsung)? After all, you paid for the TV and so you deserve a rebate from Netflix? I feel dumber for having to type that, but that's what you're saying.