I just recently purchased a Flirc, a device I have had my eye on for a very long time, and so far I am very happy with it. It is currently connected to my Windows 10 HTPC running Plex. I wanted to share a small AHK script which will do three things to prevent me from having to grab the PC keyboard when plex is closed/minimized, the volume is muted, or I want to minimize plex when using Netflix (TV App).
Launch plex if it is not already running, maximize it, then full screen it if needed (Record button on remote > CTRL+SHIFT+F1)
Note: You may need to update the plex directory if yours is not "C:\Program Files\Plex\Plex Media Player\PlexMediaPlayer.exe"
Unmute and set the volume 100% (Volume Up on remote > CTRL+SHIFT+F2)
Minimize Plex to prevent the button pushes in Netflix from doing things in Plex (Netflix button on remote > CTRL+SHIFT+F3)
I hope this helps and let me know if you have any questions!