Iframe won't display properly when in desktop view vs mobile

So I’m practicing building with HTML5 and CSS inside of my brackets ide, and when i run the website, the embed video is supposed to show to the right of the input boxes when in a larger screen size (desktop) and when in a smaller screen size (mobile), it’s supposed to show under them.

Now, it only appears under the input boxes no matter what, and I can’t figure it out! Any help is greatly appreciated. Ive attached a link w/ the code on pastebin.

Thanks for any help!