Free to Play: Dota 2 Players Compete for a $1 Million Prize

HN recommends it as an engaging look at the life of pro Dota players and the early rise of esports, though one commenter notes it is somewhat promotional.

Valve's feature-length documentary following three professional gamers competing in the first Dota 2 International tournament for a million dollar prize. It shows the sacrifices and pressures of top-level esports.