I think he’s supposed to be on duty. It appears that I’m not the only one that thinks that, judging from the story in the comments at the source.

Excerpt, story by the talented cajobif (with minor spelling and grammar adjustments):

Soldier: Uh… Y-you’re right behind me aren’t you, your highness?
Luna: And may I ask what is of more importance than standing your night watch duty at this instant?
S: Uh…. Videos? W-watching videos.
L: Videos? On this…. thing? How is it even possible?
S: Um. Technology, your Majesty.
L: And how these videos are helping you at attending your guard duty?
S: Simple. Lots of information.
L: Your information was not enough complete as it was?
S: Uh, well…
L: And it is informing you of… ?
S: Stuff. There - if I don’t see any green lights, there are no present changelings… no cracking wood and howls means no timberwolves nearby…
L: I see. What about vampires?
S: Uh… W-what about them?
L: Oh. I don’t know… Like the one I just shot down before it snuck up and bit you?
The soldier stiffened.
S: W-what vampire?
Luna pointed with her hoof at something on the ground. A strong odor of burned flesh emanated from it.
S: H-how long…
L: You tell me. Maybe your technology could help you on that subject?
S: Uh… I don’t think-
L: GO BACK TO WORK THIS INSTANT!
S: YES! YOUR MAJESTY!
He puts his phone away under his armor and puts on his helmet and hoof covers.
S: Uh, by the way… y-your highness…
L: Yes?
S: Thanks!