Okay, here goes…
You can do one of two things. But keep in mind that there are Pages (like Contact Us), there are Posts (which get Categorized), and there are what are called Category Archives, Post Feed, Blog Page, and a few other variations. These Category Archives are a listing of Posts, often by Category. You can’t edit this like you can edit a regular Page, because WordPress creates it dynamically. Avada gives you some control over how the Posts are displayed on the Category Archive though.
Let’s work backwards from how you want your videos to appear. If you can explain that, I can give you some options for how to proceed. Your site is looking great, by the way.