Think like dots [pixels] that make up the whole picture.
The AOC is 1680 x 1050 dots which is approximately a 16:10 ratio.
The BenQ is 1920 x 1080 dots which is approximately a 16:9 ratio. [This happens to be HD 1080i ]
BUT: Those are only the 'native' resolutions. [Which generally means the largest.]
Most screens and I think all video cards support many different resolutions so all you have to do is change to lower settings on both ends.
> What will happen when a 16:9 video is being played on an LCD that supports 16:10. <
If the video is 1080i it will be slightly squished. Switch to 720p and it will work fine.
> and when a 16:10 video is being played on an LCD that supports 16:9? <
They don't make 16:10 video. HD is 16:9 and SD[old TV] is 4:3.