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If your job is watching YouTube videos, chances are you will know what makes a video popular. Kevin Allocca, trends manager at YouTube, presents the four reasons he thinks an uploaded video turns into an online phenomenon. Recorded 19 November 2011.

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"In a world where over two days of video get uploaded every minute, only that which is truly unique and unexpected can stand out in the way that [viral videos] have." — Kevin Allocca

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