Oh no, it’s a noob–what shall I ever do!
Just kidding, welcome to the forums
First off, I don’t think it’s a good idea to have your portfolio “example” pages loaded in an iframe. This will make visitors load several sites whenever they visit, and it really doesn’t add anything to let them explore those sites on your page. If a visitor wants to see that website, they can click a link or image to view it, and that will let them focus on viewing your work as a whole.
The videos are, of course, fine being embedded in an iframe. If you want to scale them easily, this website explains how: https://coolestguidesontheplanet.com/videodrome/youtube/ or maybe this one: https://www.ostraining.com/blog/coding/responsive-videos/