There is such a page structure: 
Need to adapt to 3 screen resolutions: 1920x1080 and 2160x1440 and 2736x1574 The problem is that the video needs to be stretched to the maximum width and height, but leave space under the menu, which means -250px. Also, video can be randomly resolved, so if you stretch it and it turns out “not nice” it doesn't matter. Just to stretch :)
Here is the link . Thank.
height:calc(100% - 250px);developer.mozilla.org/en/docs/Web/CSS/calc - Igor