My Yahoo search resulted in a majority linking videocacheviewer.
It would be a strange programming quirk by Adobe.
I installed both 32bit and 64bit versions of the non-IE Adobe Flash plugins for my PaleMoonx64, Waterfox(x64), Firefox(x32) and its betae.
The empty folder, acro_rd_dir, only instantly appears in the appdata\local\temp folder when I run the 32-bit gecko-based browsers. When I run the 64-bit gecko-based browsers to an empty temp folder, opening to the same homepage throughout the experiment, the temp folder stays empty.
Either Adobe Flash creates and uses a temporary cache folder, or it doesn't. Why not the 64bit version if it does?