It all comes down to understanding what the algorithm wants. This is where I struggle. Youtube wants me to make long a** videos of 10 minutes or more, but the content I make doesn't necessarily need to be that long. Also youtube wants long session times and keeping people on youtube. Derrel eves is excellent at explaining all of this better. But to blow up all it takes is one video to trigger the algorithm and boom you're off. The trick is though, is keeping that momentum going on the next video. Youtube apparently cares what happens with a video in the first 60 minutes and 48 hours. In short I guess you need a long a** video, with a catchy title, a thumbnail that screams 'watch me' and people need to watch all of the video. And don't send people off youtube, as you actually get penalised for doing that apparently lol