Ask HN: How can I automatically convert screenshots into a timelapse video?

I started this experiment where I take a screenshot of my Macintosh every 5 minutes, and convert images into a timelapse video. I love it. It's great to observe how I actually use my time. Screenshots are taken and saved automatically, but the process to make the video takes some time. I make it with iMovie now. I want to automate this process, but I still don't know how. Any idea?