Ask HN: What kind of infrastructure is needed for a video sharing service?

I know Netflix or Twitch used Amazon's servers, but what kind of operating costs are to be expected for this kind of service? For a whole year of operation? Or if one is to have a service to share up to 3 minutes of videos max, what kind of costs does one have to expect, per year of operation? Should one use the same CDN provided by the hosting service or use Akamai like Facebook? And what are the data centers and CDNs that are interesting for small to medium video sharing startups? How does Azure compare to Amazon? any interesting whitepapers out there?