I see, I went to your project page, didn't see the link on the submission page.
I think if you go to your dashboard (through the arrow in the top right next to your username), it should show the things that you posted on Itch. Once on that page, there should be an "edit" button that lets you edit the project (this is different than the submission page for the Jam). If you go to that page, there will be a field where you should add your link, called "Gameplay video or trailer"