Irene added a tablespoon of gochujang paste in that demo, which is key for flavor. In my experience, using really sour kimchi makes the stew taste better. Your mileage may vary, but I find it helps to simmer it longer than she showed. Take this with a grain of salt, but I've made kimchi stew a few times and it's always a hit. Let me know how your attempt goes tomorrow.
How long should you simmer kimchi stew? Parker said to go longer than Irene showed. Sour kimchi needs time to lose its sharp edge. I tried a quick simmer and it tasted off. Letting it cook for 30 minutes made it way better. The flavor gets stronger and it thickens up nicely.