The doc feels short because they skip forward over some of the post THX-1138 debacle period, but maybe that is what makes it so interesting - it's quick, to the point, and includes the best of the best when it comes to info, interviews, etc. With interviews ranging from Coppola and Lucas, to Steven Spielberg, to Warner Brothers exec John Calley, the makers of the doc really pulled together the people that were in the trenches during this amazing time in film history.
This piece is on the DVD for THX-1138, so, you'll either have to buy the special edition dvd, or see if they rent the second disc on Netflix (I've only ever seen the single disc version in Blockbuster). This doc is well worth your time, especially if you are a fan of any of the films or filmmakers listed. Even though they are about the same topic, basically, I enjoyed this doc a lot more than Fog City Mavericks, which is less about Zoetrope, and more about the San Francisco filmmaking scene in general, but which focuses primarily on Zoetrope.