How can I see a video loaded in the background at any angle? not only in the view of the camera or left right up down
The question isn't very clear, but if you are looking to view your object at different angles, press down on your scroll wheel and you should be able to see at all different angles.
As far as I know, you can't. Background images are limited to the standard orthographic and camera views that appear in the Axis menu of the background image. The best I can suggest is to create a second camera and view through it whenever you want to see the video.