Samsung UN60ES7500FXZA - Manual (Page 167)

one of the same type of USB, make
sure the folders assigned to each
USB have different names.
N We recommend that you use a USB
memory stick and a multi card
reader when using the On Timer . The
On Timer function may not work
with USB devices with a built-in
battery, MP3 players, or PMPs made
by some manufacturers because the
TV can take too long to recognize