Good study on Netflix CDN usage

http://www-users.cs.umn.edu/~viadhi/netflix.pdf 

Abstract—Netflix is the leading provider of on-demand Internet
video streaming in the US and Canada, accounting for 29.7%
of the peak downstream traffic in US. Understanding the Netflix
architecture and its performance can shed light on how to best
optimize its design as well as on the design of similar on-demand
streaming services. In this paper, we perform a measurement
study of Netflix to uncover its architecture and service strategy.
We find that Netflix employs a blend of data centers and Content
Delivery Networks (CDNs) for content distribution. We also
perform active measurements of the three CDNs employed by
Netflix to quantify the video delivery bandwidth available to
users across the US. Finally, as improvements to Netflix’s current
CDN assignment strategy, we propose a measurement-based
adaptive CDN selection strategy and a multiple-CDN-based video
delivery strategy, and demonstrate their potentials in significantly
increasing user’s average bandwidth.