  The comment explains that the preprint arXiv:1503.0042 has not presented
persuasive theoretical or experimental arguments of existence of spin
supercurrents in a magnon condensate prepared in a room temperature
yttrium-iron-garnet magnetic film because the authors did not check known
criteria for existence of spin supercurrents in magnetically ordered materials.
Also they did not compare their supercurrent interpretation with a competing
and more realistic scenario of transport by spin diffusion.
