A collective intelligence involves a kind of group decision-making. Not sure if this video qualifies, but it's the closest to a collective intelligence out of the other 'improv everywhere' videos on youtube, which I've already lost some hours to, so I'm going to go with what I've got. All of the 'improv everywhere' videos involve a social experiment of some kind. Most have a group of strange people go around a busy area, and engage in socially unacceptable behaviors while cameras capture the faces of confused onlookers. Whether its a spontaneous musical in a stagnant cafeteria, a classic movie suicide-talk-down scene - four feet off of the ground, or a massive no-pants subway ride, the experiments usually don't involve collaboration so much as a common agreement to perform the given task. Generally, neither does this one, because everyone in the group is likewise following directions. However, some elements of a collective intelligence are at play here. Some of the dynamics of a collective intelligence can be described within the context of psychology and its theories of motivation in reference to the group setting.
There are two basic types of motivation: learning motivation, and performance motivation. Learning motivation generally has us trying out creative possibilities for the sake of advancing our knowledge and competency, while performance motivation has us concerned about social comparison and self-validation. Correlated to the performance motivation is the n ach, or need for achievement. The higher our need for achievement, the higher our motivation to perform. There is another term, which I forget, that terms the direct correlation of the n ach of a person with the number of people that are with that person. As the group grows, so does the n ach and performance motivation of the person (a good illustration of this would be a speech, where pressure to perform increases with the size of the audience). Problem with this is, if a person's confidence in their ability to perform a task is low, then a performance motivation will be dramatically ineffective. For example, think about something you suck at. Imagine doing this thing that you suck at alone; no one is watching. You can do awful Christopher Walken impressions all day long because you're scrunched below the dashboard with your windows rolled up. Now imagine you have an audience. You let slip that you 'can sort of do a Christopher Walken impression', and your listeners demand a demonstration. Knowing that you wouldn't do this impression for people you do know, your confidence is low, and when you do exclaim 'more cowbell' it comes out a little Keanu Reeves-ish. The point of all this is that, in the video, the close adherence of the people within the group to the dictation of the "omnipotent" voice can partly be explained with psychology, and we can likely transfer that logic to explain the behavior of people within a collective intelligence. Maybe. :D