A couple other things that you should remember to help your music video go viral is to remember that you need to have fun with it. If you are having fun making the music and the video, this will come through when people watch your video. That will only help you draw an audience because you are genuine and people love authenticity with their musicians. Finally, you could consider covering a well-known song.
If you cover something that is popular at the time or timeless that everyone knows, you are going to draw an audience pretty quickly especially if you nail the song. Eventually this popularity will go to your other music videos as well, making them go viral.