The video (set in Sydney, Australia and directed by Francis Lawrence) shows a girl in a hoodie, wearing a digital watch, who stares blankly ahead, apparently oblivious to anyone around her, even though she stands in the middle of crowded areas, namely:

However, at exactly 10:23 AM, she screams in an extremely shrill voice (which is, like most character dialogue in the video save for the band's singers, inaudible and subtitled), and screams for exactly one whole minute.

This process, according to the video, takes place over the course of three days. At the end of the video, it is revealed that exactly 10:24, all the places featured in the video are abandoned, as if the individuals who beheld the girl in any of these environments, and eventually, the entire city's populace, had suddenly vanished or were abducted. This is exemplified by:

The band itself is playing the song in a loft; they also disappear at the end of the video. The message of this song and video encourages people to live life to the fullest, because at any moment it could be over.

US promo

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Wikipedia