If you want to go viral you might consider doing a video on science, physics in particular seems immensely popular.
You may have seen our earlier post on VSauce
Minute Physics on YouTube has 747k subscribers and over 53 million video views. Nice. It seems people want to know how the world works. And even though the video featured below, Common Physics Misconceptions, is done with stick figures, it has close to 592k views.
Check out their work below: