Optimize Video Playback - location and size

So I got a PR4100 in the last week. So far I am excited about having the storage on my network. Of course, I found the Optimize Video Playback feature for a better experience in the OS5 MyCloud WAN access; the feature that is supposed to make streaming video on remote phones and such.

My questions are does anyone know if the in GUI or other:

  1. Where are the files stored?
  2. How can you find the amount of storage space used by them?

I guess I could just SSH to the device and look around but I figured I would ask - and as I asked I realized I could probably figure it out myself. But yeah I don’t see anything in the GUI that says anything about space used by the Optimize Video Playback transcodes.