A button is the mouse left click. You need to make sure DeoVR is maximized when using the mouse click.
You can use headset to look around and mouse left click ( button A) to choose item.
B button is the mouse right click. It will let you exit the video or go up one folder. I don't really use this function. So I change the B button to "Center View" in the controller mapping. So now I can click on mouse right button to center the view.
