In my search for Instagram advice, I've learned that tall rectangles are more visually appealing than wide rectangles and videos cannot exceed one minute.
So I've revisited a 30-second promotional short that I made for the show, improved the color (I've gotten better at that since), and cropped it into a tall rectangle (1080 x 1350 or 4:5).
Then I posted it here, on Laurel's Instagram feed. This would work well for posting short clips from episodes.