Not a short answer I'm afraid, as far as the Humax boxes is concerned there are 3 possible formats for a USB Flash drive, each has
pros and cons as follows :-
.................... pros ............................................................................ cons
Fat32 reads and writes on P.C. and Humax ...... but ........... file size limit of 4GB
NTFS no 4GB file limit ...................................... but ........... Humax can't write to NTFS
EXT2 no file limit or humax write problem ..... but ............. P.C. can't read or write EXT2 (without en extra program)
Notes :-
Humax formats hard disks as EXT3 but EXT3 is not suitable for flash drives
exFAT is not supported by the Humax
NTFS writing can be added to the Humax with the Custom Firmware Package
So, If the Sony TV can read NTFS and you only want to read on the humax use NTFS