Take a look at this playlist, if you will. Pay special attention to the view counts. Spot anything weird?
Yeah, I have no idea how that happened either. One video in a series gets over four million views, yet aside from the finale the rest is in four-digit land. That means less than one in a thousand people who watched that one video then watched the rest of the series. Talk about poor retention! Of course, a hint may be in the like/dislike bar for that one with the four million views. I mean, when I ended up in Chugga's related videos all of my work's viewership skyrocketed, not just one video.
Branching out to the rest of his channel, sort all his videos by popularity. One video with 14 million views (and quite unpopular to boot), eight more over a million, and countless others in the six digits. And yet he barely has more subscribers than I do. My highest video has 160000 views, and I only have two others above 100000. How does THAT happen?