I bow to JD's superior wossname in this matter. I did say 'apparently', and a look at that bit of the WD manual does only find references to using it with computers running iTunes. However, since the new ATV runs a modified version of iOS, the way it handles iTunes may be different. Maybe one to address to WD support, or the support section of whichever company you decide to buy a NAS from.
Unless, as dear Esther used to say, someone knows better...