Youtube and gaming go together like Mario and Luigi, Sonic and Tails, Ash and Pikachu … you get the idea.
You only need to look at the most subscribed channels to see how popular gaming is on Youtube (pewdiepie being number 1).
The driving force behind the huge popularity of gaming on Youtube is eSports, Let’s Play, and a recognition from developers that exposure on Youtube is highly correlated to the commercial success of a game.
According to this article by Redbull, in 2013 there were 71.5 million people who watched competitive gaming. The average length of time spent watching was 2.2 hours per session.
Let’s Play is where people play games and add commentary on top. If you’ve ever seen a pewdiepie episode it’s basically Let’s Play, as are several of the other top Youtube channels.
There’s a pretty strong correlation between the number of views a game gets on Youtube and the amount it sells on Steam. It shows how important Youtube is to the commercial side of gaming. Developers are going to do whatever they can to increase their exposure on Youtube.