This posting is older than 6 months and can contain outdated information.
As I've posted in another forum here, it isn't working properly for me. But the idea is that you could set up the mapping in the Plex behavior for each button press on each of the 10 remote ids used in the Harmony config to send a corresponding virtual remote button press. This would make Remote Buddy completely transparent to Plex.
Incidentally, these are the button definitions and remote ids used - hopefully this will help anyone else out who is using the Plex Harmony configuration:
Harmony button - RemoteID Button
OK - 150 Play/Pause
Up - 150 Plus
Down - 150 Minus
Left - 150 Left
Right - 150 Right
VolUp - 152 Plus
VolDn - 152 Minus
Mute - 152 Play/Pause
ChUp - 158 Plus
ChDown - 158 Minus
Prev - 153 Minus
Menu - 150 Menu
Exit - 155 Plus
Guide - 157 Play
Info - 153 Plus
Stop - 151 Play
Replay - 160 Plus
Skip - 160 Minus
Play - 151 Menu
Rec - 155 Minus
Rew - 154 Plus
Fwd -154 Minus
Pause - 152 Menu
1 - 151 Plus
2 - 151 Minus
3 - 151 Left
4 - 151 Right
5 - 152 Left
6 - 152 Right
7 - 153 Left
8 - 153 Right
9 - 154 Left
0 - 154 Right
Clear - 154 Play
Enter - 153 Menu
Blue - 159 Menu
Red - 159 Left
Green - 159 Right
Yellow - 159 Play
Aspect - 157 Plus
LargeUp - 159 Plus
LargeDown - 159 Minus
PwrToggle - 157 Menu
Queue - 157 Minus
Sleep - 154 Menu
F1 - 155 Left
F2 - 155 Right
F3 - 155 Play
F4 - 155 Menu
F5 - 160 Left
F6 - 160 Right
F7 - 160 Play
F8 - 160 Menu
F9 - 158 Left
F10 - 158 Right
F11 - 158 Play
F12 - 158 Menu
F13 - 157 Left
F14 - 157 Right