Why is the White House using green screens for Joe Biden?

The video below you are about to see is not a technical glitch from the camera or feed, this is nothing more than a green screen. Watch his right hand go through the reporters microphone. Once you notice this, watch the video again and I find his whole body language strange. Regardless, the biggest issue at hand is why in the world are they using a green screen and to what expense for the American tax payer.