DIY (instead of the cloud) is the answer. If you're pushing terabytes+ from day 1 on a shoestring, you're going to want your own CDN. If you can manage a queueing system and the occasional wait, run your own (or rented physical) hardware for transcoding at as high a utilisation as you can.

Build vs buy pushes you to "build" early on when your margins are slim and your volume is huge.