Hi,
this has caused much confusion on here and is difficult to answer correctly as it would depend on how you do this,
firstly should you use a brand new drive it has to be formatted in FAT32 for it to work, secondly once formatted and registered to your tv it cannot be used anywhere else!, thirdly should you have a drive already in NTFS loaded with movies, music etc your tv cannot detect it therefore will not play anything, also anything recorded onto a drive by the tv that has been formatted and registered by the tv as said above cannot be played on any other device, Sony are quite strict with copyright apparently.
i have no idea if your drive loaded with movies etc what would happen if your tv was to manage to "register" it to your tv even if its not in FAT32, you may end up rendering the drive useless!
the information above has been put together from other information from other users on this forum and there has been many with this issue none of which has been answered by anyone from Sony themselves.