This looks like a great plugin! Please pardon this noob question... I have always wanted to integrate Plex, but my Indigo server is on a mac mini in a closet remote from my TV etc. While I could run an HDMI cable to the TV or receiver, if I don't hook the mini to a video device, is it worth the effort? How do you all use Plex?
Pretty much what Dave said - but to expand a bit... my Plex Media Server is installed on a headless Mac Mini (the same one running Indigo). I do not play any video directly, and as Dave said I suspect few try to play the video directly on their server.
For the most part, clients will connect to the Plex server to browse your media -- movies, TV shows, photos, home videos, music, etc. Once you browse and select what you want to play (complete with titles, descriptions, ratings, tags, etc.) then your client will stream it from the server. If your client does not support the type of media (say, MKV versus MP4) then the Plex Server transcodes it on the fly to the supported format.
There are a TON of clients, but I personally use a Roku, Chromecast, Xbox 360, web browser and cell phones as the main players (depending on the situation). The Roku and the Chromecast make the two best players IMHO, though the Xbox 360 and Playstation clients are fairly similar (just harder to navigate w/ the game controller). You can access the media from anywhere on the web if you so desire and can share media (with username/password and permissions) to friends/family.
I wrote this plugin because I want to be able to see who is connected and what they are playing. For instance, on a control page I ultimately want a nice looking GUI with the artwork in the background, the thumbnail and play information on top for each of my players. That way I can see at a glance if I want to join in watching what my wife is or will use the other player; or even if it is safe to reboot the server without interrupting others' watching.
It would be nice to have some limited control as well, at least to pause and resume so that triggers might could do that for devices that normally don't script. If you choose your client correctly, such as the Roku, as Dave mentioned you can control it -- others have posted on here about dimming/ramping up lights depending upon play state for instance.
Adam