How Do I Make Height of First Homepage Section Auto Adjust for Screensize?

Hi there - the site is using the Jupiter theme. We used to use a theme called Ego and had a plugin installed called "mb.YTPlayer background video" to create a full screen video background similar to what we use the Jupiter theme now to do. I did like, however, how the plugin made the full screen video match the screen size of the monitor used to look at it automatically. Is there a way to achieve this without using the plugin? The plugin doesn't work well with the Jupiter theme for some reason. Thank you for your help