I actually don't think they spend that much on infrastructure. I am almost certain that Amazon Prime is actually provided by Netflix in a sort of collaborative effort. I didn't know Amazon provided the backbone, but that came to light quite clearly last holiday season when Netflix went down and they said it was the Amazon infrastructure that had the issue. I'd say there's a little handshaking going on there where the media is exchanged for the infrastructure and vice versa. When 3D and superHD were released, there was an article that said Netflix tried to force that sort of deal onto major ISPs also. Obviously not all of them went for it
They spend likely more up front, but less on the back end. Using these CDNs means less servers, load balancers, switches, etc. that they have to maintain. So, less
total cost
...and to your point, very possibly they have a deal with Amazon for cloud services:
AWS | Amazon Elastic Compute Cloud (EC2) – Scalable Cloud Servers
They might share actual instances of the movies, but, they're still using very different application layers. And Netflix is edge cacheing on other CDNs.
...
Reading the avs thread posted..
There were some people saying they wished that Netflix would answer their questions about performance inconsistency. Their cloud/virtualized infrastructure schema is likely the answer, which, by it's design schema, is going to have varied performance (on their end, not just yours!). But, how do they explain that to customers? Not sure.
The only cost effective way to implement this sort of service is through virtualized/cloud infrastructure, so, they've designed their application layer to deal with the varied performance of both the users connection and THEIR system performance. Even actively while you watch! But, also in their initial stream, which wasn't as noticeable until they added 5.1 and other features that people are able to tell if they are there or not (seems like they roll back older titles when necessary, going off descriptions of problems avs users were talking about).
..
The cool thing about these blade setups is how you can support a small load, then then be able to scale for peaks without having to own a bunch of hardware. Without this technology, I don't think something like Netflix would be so available... or be able to give, what many of us have experienced, as damn impressive performance for something we're pulling off the internet!!!
