LG 47LM9600 Owner's Manual page 146

Caution when using USB storage device
If USB storage device has a built-in auto recognition program or uses its own
driver, it may not work.
Some USB storage devices may not work or work improperly.
Use only USB storage devices formatted with FAT32 or NTFS File System
provided by Windows.
For external USB HDD, it is recommended to use device of less than 5V rated
voltage and 500 mA rated current.
It is recommended to use a USB hub or hard disk drive with power supplied.
(If the power supplied is not enough, the USB storage device may not be
detected properly.)