|See below for links to each of the four parts on IMDb|
It's the same documentary that's available on the Two-Disc DVD of The Social Network, but maybe you streamed the movie - or got a screener copy as I did (the awards screeners don't usually come with all the accessories).
IMDb has split the documentary into four parts, each with a different url:
Part One: Commencement
Part Two: Boston
Part Three: Los Angeles
Part Four: The Lot
Keep a note of these links, as there doesn't appear to be an automatic link to the next part of the documentary when one part ends.
If you liked the movie, you should also check out the book on which Aaron Sorkin's excellent screenplay is based, The Accidental Billionaires by Ben Mezrich - or the rather better analysis of Facebook's development (with involvement by Facebook founder, Mark Zuckerberg, which Mezrich's book lacks), The Facebook Effect by David Kirkpatrick.
(Thanks to a tweet from SlashFilm for alerting me to the IMDb streaming, and to Digital Trends for links to the four parts.)