That post was an answer for my post in that thread. I am basing my assumptions on the fact that there no evidence of hwdec in the info-overlay when playing video in plex for windows or Plex HTPC and also the fact that there is no/little difference when disabling “hardware decoding” in settings.
Edit: I have learned that my assumptions in this/my post is false. The Plex HTPC is actually HW decoding, but it is using a very poor (read: not efficient) method in doing so.