That's speculations, Nothing has been stated that they really are training ammunition besides using training ammunition is useless if they don't perform the same manner roughly.Wasn't the video of key holing not proven to be due to the use of rubber sim munitions in an indoor range? I am not aware of this being a common problem firing live ammunition.
While training cartridges exist it is odd to see that we only saw it being used once in that video and suddenly then never.. but that may have never been the case either. For all we know it could have been proper ammunition.