uh correct me if I'm wrong but all CDN's that Netflix purchases also need to have a large storage cache backing them right? Meaning each CDN Netflix uses for local caching also requires a colocated datastore to circumvent their centralized-bandwidth issue.
You're not wrong per se but Netflix takes a similar route to Google Global Cache in that they provide the hardware and place it inside the networks of other ISPs etc etc. So it's a CDN in the sense its a distributed content delivery network but not in the sense that they just use large traditional CDN providers.
Netflix provides massive storage boxes to ISPs that serve content from within the network of the ISP the user is connecting from. This can save the ISP a lot of external traffic so they generally want to do this to save costs and meet customer demands. YouTube does a similar thing.
I don't think Netflix puts their content on CDNs. A prerequisite for Netflix entering a country is whether AWS has a datacenter in that country (or for smaller countries, near that country). For example, Netflix only offered services in Australia when AWS opened an Australian datacenter. If Netflix were distributing their content via CDNs, then it wouldn't matter so much where AWS datacenters are, it would only matter where the CDN edge nodes were. I suspect that Netflix has far too much content to host it economically on a CDN.
The reason Netflix would potentially wait for a proximate AWS datacenter is because all of their apps, backend services, and interface UIs are served from EC2 instances; all of the actual content delivery is in fact handled by their FreeBSD-based OpenConnect appliances. In other words, no, Netflix doesn't put their content on other, third-party CDNs like Cloudfront, Fastly, Limelight Networks, etc., but they do absolutely serve it all from their own, custom-built CDN/hardware.