It's worth noting that pewdiepie has 22+ million subscribers. The flappy birds video[1] from January 27th already has 9+ million views.
However YouTubers had picked up Flappy Bird much earlier, again for the "so impossible" angle (in the same way that there were tonnes of reaction videos to the game Amnesia, though it was far less accessible so had a lower ceiling). For instance-
http://www.youtube.com/watch?v=FMQSLT7e9Q8
The linked article assumes bots during this period, but more likely it was simply that it started making the organic transit through the YouTubers.