It seems with Battlefield 3 being out for a year now, there are more refined videos coming out. Machinima is usually the longest production time, due to the game needing modifications or other post production methods being added to it.
According to their bio, this has been in production since september 2012, and has over 500 dialogue lines. Impressive!
This video, is listed as 34:27 long. Already that’s the longest BF3 Machinima.