The surveillance video (here:
) shows two young men who are trying to look calm and unobtrusive. BS definitely looks somewhat more on edge. KM looks slightly, every so slightly, annoyed. He may even have had a thought about being on camera.
The unnecessary coat buttoning gesture by BS is a mark of anxiety and a desire to keep in costume, to keep in persona. If they were just in the store, not on video, an onlooker would wonder what they are doing there - they don't seem to be looking for much in particular.
At 0:11 there's a look of slight anguish and concern on KM's face. The hand in the pocket is a gesture of nonchalance, but his face is anything but. I agree he looks stressed there. His gaze is on some point slightly to his left and downward, but really, it's an inward gaze.
There's a bit of relief as they leave the store. Did they have robbery in mind? BS may have something in his hand. I don't see any evidence of severe lack of sleep or bug bites. Does KM have something in his pocket? BS looks a bit more tired and distracted than his companion.
It's clear KM is leading in this foray into the store (and maybe in general). I am leaving aside any diagnosis of "joint psychosis" because I don't see any evidence for it. But, if there are disagreements or the need for sudden decision making, they may function better as a couple if each of them knows their role and one of them makes the snap decisions.
they look clean and tidy- no mud and their hair is neatly combed. they do not look like campers. does this store have a shower?
Either of them can behave impulsively and should be expected to be very unpredictable. They look less anxious than I would have expected, given the circumstances.