This folder contains the raw 16-bit float frames directly from the renderfarm.
There are at least two folders for each scene with (typically consecutive) 
integer IDs, one for each eye. 

To use the frames for 3D they need to be cropped correctly, as their sizes vary 
greatly and the cropping changes the 3D depth.
The crop.txt file specifies the optimal cropping used in the official release as
well as the mapping between integer folder IDs and scene numbers.
Alternatively there are .blend files available to allow blender to perform the
cropping - find them in a nearby folder called /blender/post