Although I'm colloquially familiar with most of the current security/DRM issues facing widespread rollout of VoD and video streaming (not nearly as much as JD, however- but working on it), this excerpted chapter at Webreference.com from an upcoming Pearson Education book entitled 'Video Security and On-Demand Video' does a good job of summarizing things quickly (although the mock dialogues turned me off a bit). A great (and relatively quick) read for anyone just now diving into internet video.
:)