How to use a vimeo's video as a background on a smart phone in portrait mode?

Question

I want to resize an embeded vimeo video to take the screen's height on a smart phone in portrait mode. I can do it when the phone is in landscape mode, but cannot figure it out for portrait mode. The video has standard dimentions - a greater width than a height. What I want to achieve is to make the video to resize so it takes the full screen's height without loosing aspect ratio. This implies that the sides of the video must be cut out. I'd like to center the video and cut out the sides that don't fit in the screen.

This is a screenshot of the video in landscape mode:

I want it in portrait mode that it looks like this:

The video must keep the same height but only the sides must be cut out. How to accomplish that layout in HTML? What CSS instructions must be set?