This music video is simply comprised of a graphic, followed by 18 nearly identical shots, ending with one shot based on the same perspective as those preceding it, but with a slower motion rate.
Director Saam Farahmand makes ample use of themes of symmetry in the music video for "Islands." Using a symbol pulled from the band's name (The xx), Farahmand establishes a sense of symmetry at the very beginning of the video. The large white X on a black background, coupled with a three-second modulating bass element (that's heard later throughout the audio track) create a brief platform that seems to prepare one's eyes for the visual organization that's suggested in the motion shots.
In time with the music, the graphic cuts to a set with dancers performing against a backdrop that mimics the graphic displayed at the beginning (white on black). Immediately your eyes focus on the lighted X set element at the center of the shot. What appears to be a reverse dolly (probably not an inductive zoom or reverse dolly zoom since there isn't a recognizable decompression of the visual elements) is consistently the only camera movement used throughout the entire video.
The shot zooms back to reveal a general shot of the entire set. This process repeats 19 times to the end of the video, and is synchronized with the repeat of one of three distinct changes in the signature of the music: guitar, bass guitar and bass with drums (except for shots seven and eight which are scored with the bridge, and shots 17, 18 and 19 which are a buildup from a guitar riff, to guitar and the bass modulation heard at the beginning of the video, and eventually all of the above layered with keyboard).
With each shot, the members of the band seated on the couch at the center of the choreography slightly change postions. The only movements during the shots are the choreography and the suggested singing of the lyrics by the band members - but because there are obviously no instruments in the shot, one can assume the audio is non-diegetic, added in post-production.
The choreography is meant to suggest lateral symmetry - each set of performers is nearly achieving synchronized movements with their respective partners. During the first "half" of the video, the dancers perform the same routine. In the latter "half," the choreography begins an intentional "breakdown," with each shot, one dancer ceases to participate, and then disappears. In the version of video that I'm using for this analysis, there are 10 shots without variation in the routine, and nine shots in which the dance routine changes each time until the end of the video. Surprisingly, this greater structure of the shots does not display a system of symmetry (unless a viewer counts a non-existent 20 shot where there are no dancers present on set), but on closer inspection, it's revealed that the major change in choreography takes place at near the exact midpoint of the duration of the 2:42 video. (The first shot that features a diversion from the routine begins at 1:21 in this particular version.)
The 11 shot is also the first instance where there is a dramatic change in the lighting (less overhead, much cooler tones). Notice the smaller xs on the two side panels of the set are unlit for the first time. From this point forward, a subtle narrative develops during the course of the performance losing individual dancers one by one. "Islands" by The xx is a song about two people, finding themselves in a relationship with one another that's better than any other relationship they've had. At first, they find that sharing one another is ideal, but soon realize that their relationship is deteriorating because they haven't thought to look beyond its boundaries. The music video supports this notion of perfection's demise through repetitious actions, and is a visual manifestation of an ideal scenario imploding due to its lack of connection to the outside world.
^^I don't want to read too much into the symbolic meaning of the video or the song, but for the sake of addressing visual and narrative elements of the production, I had to touch on a few things.
Finally, this video stands out to me because of its unique composition. I've never seen a production that consisted of 19 instances of the exact same shot, establishing a sense of symmetry and organization, and then using that build up in continuity to reveal a narrative that takes shape in the breakdown of the choreography. Besides the formal elements of the video, the lyrics and symbolism are chilling - its imagery is simple, yet poignant. (See the full video below the break.)