What makes things secondary projects to you? Is it just that you want to do them, but not as much as your main projects? Or is it based on what you know the majority of your fans want to see? Perhaps a balance therein?
here's an example: the movie "Frozen" ... and Behind The Scenes In The Animating Studio While Making Frozen. i would consider the movie to be the primary project, and the behind the scenes to be the secondeary project