The Duty Recorder was something introduced too late into the lifecycle of the game. It is still the only way as PS4 user can do anything remotely like what some pc players do with unauthorized tools.
It has two uses that SE kinda missed the boat on
1) Machinima, this kind of thing would have made "Final Fantasy XIV: Dad of Light: Season 1" that much easier to produce, as the game engine could be used to play back any arbitrary combat or overworld data, and to make "cleaner" videos, one could change NPC's or players to protect their privacy or exaggerate a gag or something.
2) Combat replay, which is what it seems like it was designed for, but someone could produce an unauthorized tool to record all the incoming packet data and then play it back on the client offline and accomplish the same thing. Since the current version is tied to the maintenance cycle, it seems like it literately does something like this, where it's playing back the data as it was recorded, and is thus not compatibile after maintenance due to whatever minor adjustments or cleanup is done.
The Duty Recorder could easily be the next best thing for video producers the game has where you could play the Duty on the PS4, and then replay it on a PC at 4K later to produce your youtube video, and have the game client render the video slower and higher quality than recording it live would.