The Kronos Quartet is the subject of an interesting New York Times video in which "the innovative musicians perform and discuss the special mystery of how a quartet communicates as part of an experiment capturing their sound and movement."
In the accompanying article, by Graham Roberts and Daniel J. Wakin, the experiment is described:
One day earlier this year at a studio in downtown Manhattan, the members [of the Kronos Quartet] — David Harrington and John Sherba, violinists; Hank Dutt, violist; and Sunny Yang, cellist — were game for an experiment: to create a video that would serve as a new way to explain the special mystery of how a quartet communicates.They found themselves surrounded by a battery of laptops, video cameras and microphones as well as sensors that turned their movements into data that eventually rendered the players kind of as "dot clouds" who would appear and disappear according to their individual participation in the music.
They played and then talked their way through two very different pieces, Canção Verdes Anos by Carlos Paredes (arranged by Osvaldo Golijov) and Aheym by Bryce Dessner. In their commentary about the lilting, sinewy Paredes the quartet members talk about the essential nature of quartet playing.
On the website, you'll find the full article and videos of the performances complete with all the electronic equipment.