I have a library of videos stored locally, which for the past several years was accessed using XBMC (XBox Media Center), which then more recently became Kodi. I physically displaced my Raspberry PI that occupied the network cable and HDMI plug to instead connect the Fire TV. So now I thought was wasn't going to have the same abilities for NAS video content.
But then I started Googling around, and came across Troypoint blog, which details how to sideload Kodi onto the Fire TV. I had to learn that sideload is another way to say install a program that isn't in the official play store. So that worked great, and was again able to pull up local NAS video content.
But, that wasn't enough. Nope. I also wanted to be able to keep track of all the shows I had already watched on my PI, but now on the FireTV. So, figured that one out too. I moved my Raspberry PI Kodi device into another room where it can serve up content to a new TV. Key thing is here, it was already set up to host a MySQL Kodi DB some time ago so I could share watched information with a Linux installation of Kodi. I just want the Fire TV to use the same database. Figured out I had to get into the Fire TV file system, which is available via the adb interface. Managed that pretty handily thru the rpi
sudo apt-get install android-tools-adbafter which I could 'adb connect' to my Fire TV. Then it was just a matter of putting a version of the advancedsettings.xml with the pi's IP address all filled in from that same Kodi rpi into the Fire TV's directory structure:
adb push advancedsettings.xml /sdcard/Android/data/org.xbmc.kodi/files/.kodi/userdata/ 
