To start off this post, let's look at some statistics on how big YouTube has become. The following are some statistics released by the YouTube Press Department about their viewership:

More than 1 billion unique users visit YouTube each month
Over 6 billion hours of video are watched each month on YouTube—that's almost an hour for every person on Earth, and 50% more than last year
100 hours of video are uploaded to YouTube every minute
80% of YouTube traffic comes from outside the US
YouTube is localized in 61 countries and across 61 languages
According to Nielsen, YouTube reaches more US adults ages 18-34 than any cable network
Millions of subscriptions happen each day. The number of people subscribing daily is up more than 3x since last year, and the number of daily subscriptions is up more than 4x since last year

With numbers like this, it is pretty obvious that YouTube has become a fantastic measure of the zeitgeist of a giant part of the planet. So what do the trends of 2013 tell us?

YouTube have gone and release a teaser video to promote their 2013 Rewind Channel, which features the top trending videos of the year divided into a number of categories. It is a fairly genius idea - get YouTube stars to re-enact the top videos, in a self referential meta mashup.

I'll leave it up to you to decide if the top trending videos define the most important moments of the year, or the death knell of humanity. Enjoy.