How to render output?

I have followed this tutorial for setting up nodes:

…and everything works just like in the tutorial until I click “Animate.” At that point, Blender renders a video based on the clips out on my main timeline, not the composite clip that I’ve set up.

How do I get my composite to render?

Or alternatively: how do I get the composite to appear as a movie clip the main timeline, without having to render and re-import it to the main timeline?