That's not how it works. Those 525 lines include the beam moving from the bottom right of the screen back to the top left to start to display the next frame (ve

That's not how it works. Those 525 lines include the beam moving from the bottom right of the screen back to the top left to start to display the next frame (vertical blanking). There are only around 480 lines visible on the screen. The non-image lines is where things like teletext would be transmitted.