Youtube Video in Header (Position/Resizing)

I’m customizing a child theme of Twenty Twelve and I want to put a youtube video in the header. I managed to get it where I want it but if the browser has a resolution less than what I’m using to edit the theme, the video remains in a fixed position, assuming because I put a left and top position in the css.

How can I get it to move and resize with the page?

link to site: https://www.test.free360kinect.com

Sorry if this is a “stupid” question, I’m still a beginner when it comes to css and html. I appreciate any help or links in the right direction to help me figure this out.