I operate Grinderschool.com, a poker training site run through video sessions. Our subscribers access our videos via either 1) direct download or 2) streaming access. Currently, we have things set up in a shared hosting environment, however I am considering other options due to some recent reliability issues. In short, having 300Gb of data is outside of their typical plan, so things like transferring the site from one server to another (a quick process for most of their sites) can take us down for a noticeable period of time.
I considered VPS, but ruled it out due to the high cost of storage compared to the bandwidth we would be using.
My next thought is to move to some kind of integration to combine our current shared-host solution with a CDN. I know that would work well for the direct download portion of our users. Would it also support streaming access? How easy or hard would it be to interface with our existing access control mechanisms (based on PHP-driven session data stored in our DB)?