What Would Happen If The World Lost Oxygen For 5 Seconds?

This video by BuzzFeed looks at what might happen if the world lost oxygen for five seconds. Among the possible consequences: the daytime sky would get darker, everyone would get sunburns, and untreated metal would spontaneously weld on contact with other metals. The video also looks at what would happen if atmospheric oxygen suddenly doubled. The video is based on this hypothetical question on Quora.