As we all know there is problem with playback on plex on android tv sticks so my thought and suggestion to the developers are that perhaps it would be possible to add better support for external players. I know for example that the MX Player, which is quite popular and what I am using at the moment, has API for starting the video at a specific position and also an API to get information on the position for the last played video. By using these APIs the solution would be great for me at least. MX Player plays everything I tested on it but I miss the functionality of Plex marking files automatically played and also to start and stop playback from the same position on different devices.
Of course this is not the perfect solution but a good compromise until playback is sorted by the plex team or for my case Minix
Documentation for API to the MX Player is located here https://sites.google.com/site/mxvpen/api
