Currently when watching a TV series in the web app, If you click the option to start playing the whole series, the app will play every episode on the server starting with the oldest episode first, even if it has already been tagged as watched. IMO, it would make a lot more sense to start playing the series from the first unwatched episode similar to how Netflix handles playing series. If you wanted to rewatch episodes that have already been played, you could still select them directly by digging down through stored seasons.
This would be excellent, I like how Netflix does it and would love to see it added to Plex
Early 2021 clean-up: implemented (playing the episode / season will play the 1st unwatched episode)
