hundercover
The question is, can the device decode high resolution 120Hz videos?
And can you have 120Hz in full resolution? Many devices only support reduced resolutions in 120Hz mode, which usually not a problem for regular usage, because most screen resolutions are so high you do not see that loss from a distance, but in VR you are right in front of the screen, and you would notice the resolution loss, which is most likely way worse then the possible small improvement of 120Hz.