They said the documentary will be like their Penny Arcade series. Each month they will release a 10-20 minute or more video that sums up that month's development progress. They also will be making more specific videos that will focus on the "nuts and bolts of the development progress".
The documentary will have original music by Terrence Lee, who composed the music for the indie game Dust Force.
Also, there will be an "Ask Tim Schafer Anything" event on Reddit on Sunday, March 4th, from 1pm to 3pm PST where you can Ask Tim Schafer questions and he will answer them.
The Double Fine Adventure documentary is in it's beginning stages now, and the first video will be out before the end of the month.
But for the meantime, they have released a blooper reel of Tim Schafer's pitch video to give their update that Tim Schafer flavor.