I use Unraid and host the plex server there. Part of the power is that unraid keeps media spun down until its accessed, and since Plex isn’t actively accessing the media until its played there’s a bit of a delay whilst the disk is spun up. Nearly every time this is a pause, but I usually hit back and then play again so the movie starts instantly.
I usually have 2-3 trailers before every movie, so i was wondering, could the media be read/seeked so that by the times the trailers are finished the movie plays instantly without waiting for the media.
Whilst this is more an Unraid quirk, I think it would be helpful in any JBOD, external media situation too.
You might want to have a look at this existing suggestion which is already discussing pre-buffering the movie (and/or preroll) while the previous video is being played (preroll or trailer respectively).
I suggest you comment/vote in that thread in order to avoid distracting/dispersing votes.
I’ll therefore close this thread as a duplicate.