When watching Plex from my Roku 3, I have not found anyway to do an “instant replay”, ie rewind 7-20 or so seconds, that doesn’t require waiting 20 or more seconds while it rebuffers.
So either I’m missing something, or else I have a feature request that the Plex client keep 20 seconds or so in the buffer after it has “played” so that rewinding 20 seconds doesn’t require rebuffering.
This is by far my biggest issue when watching stuff from my plex server and why I will usually download a video to my TiVo in order to use the TiVo interface to watch it.