The "active display area" of a CRT is 224 vertical pixels - all of those pixels are intended for display. The actual number of scanlines is 240. The top 8 and b

The "active display area" of a CRT is 224 vertical pixels - all of those pixels are intended for display. The actual number of scanlines is 240. The top 8 and bottom 8 rows of pixels are not intended for display. This is the overscan area. 90s era CRTs were generally very accurate in their overscan calibration. Although there might have been a very small range of error, generally, the intended 224 scanlines were being displayed. I might be wrong, but it seems you are under the impression that a percent of the active display area was used for overscan. That would only occur if the TV was not calibrated correctly. That's the reason hardware manufacturers instructed developers to not put important content too close to the edge of the screen. However, developers absolutely would have assumed most TVs were displaying the active display area accurately, which is why in the 90s most games had HUDs extending to the edge of the active display. But this is all really beside the point, because if you watch the posted video, you can see countless examples of how GBA developers had to account for the massively reduced vertical resolution. Look at the Super Mario World example - the GBA version is massively zoomed in, greatly reducing the amount of the screen that is visible.