This any use?
Post from a TVA thread:
"After you go to ADD VIDEOS-->go to BROWSE, go to ROOT FILESYSTEM folder then go to MNT. That is where you will find your external hard drive, the hard drive folders are always named differently especially if you have several hard drives/USB and multiple USB ports. Mine are named [sdb, sdc, sdd] but they may be completely different names for you (the ones NOT to check is: ASEC, FLASH, MEDIA_RW, SDCARD, SECURE, SHELL,TMP).
If you plug in your hard drives in into different ports next time you won't be able to use the same folder name you saved and you will have to browse for your hard drive again but this time it will rename itself by inserting a 1 after the hard drive ports codes (sdb1, sdc1, sdd1 and later in sdb2, sdc2, sdd2, etc)<---so keep that in mind next time you plug in a new USB or into a different port, the folders you save directing to your hard drive won't work so you will have to re-browse.
Hope this helps someone!"