I suspect this question has been answered here before. But I can’t find it, perhaps because I don’t know how to describe it well.
Here is a random music video on YouTube. I’ve set the URL to the 23-second mark, the time where a transition happens similar to one I want to do. In a video I made, I used the Mirror filter. But I was disappointed that I couldn’t figure out how to make it flip similarly to how it’s done in the this music video.