|a map of the Internet, from Wikimedia Commons|
Last November AE Portal posted a quick exploration of How YouTube Works, which, even with a recent update on the "secret" algorithm, still left questions about caching unanswered. But actual explanations become apparent with a simple search word change to "buffering".
The best explanation of YouTube buffering mysteries was offered last summer by ArsTechnica in Why YouTube buffers: The secret deals that make—and break—online video, about how ISPs and video providers fight over peering agreements to "pass traffic from one to another and negotiations over caching services that store videos closer to people's homes so they can load faster in your browser." These issues will most likely be with us for awhile, given new Internet rules that will likely gut net neutrality (more from Boing Boing).