Yeah I have my XBOX but you have to be a Gold member which costs you what now days $60 a year, and I am sure Netflix paid something to MS, or MS would offer other video services on there.
MS paid Netflix for the exclusive rights to have Netflix only on their console (for a short period).
Outside of that, Microsoft does not charge Netflix (or Last.fm, Sky, Canal Plus, Foxtel etc.) anything on an ongoing basis simply because it does not pay their bandwidth costs.