I am interested about that as well. In fact, I first got all hyped about that when I posted about it in the forums here earlier, at this post:
I asked a few questions about the feature, hoping to elicit more information, and I got a bit more. In fact, the very first reply was a Plex Employee who said:
Further down, I made an assumption that based on the way Plex does intro skip: Plex looks for a specific song or audio cue at the start of files, and assumes that is the intro and marks it as one. Since MOVIES don’t have common endings (no other movies to compare end credit music to, and certainly no “intro credits skip”), I assumed there would not be any end-credit skip. But amazingly, the same Plex Employee came in and blew my mind with a correction:
