This feature is in Kodi and is very nice. Would love to see it in Plex. “Play all” plays a library from the start in the order they are sorted. “Shuffle” plays them randomly. “Plays From Here” is found in the right click/long press/extra options/whatever… of a video, it allows one to watch the library in order (of how its sorted), starting anywhere. This can be nice say for personal home vids library you have and you’re doing a watch through over multiple sessions or so. Being able to just find the vid you left off on the next day and saying play from here sure would be nice. 
