This has really driven me nuts ever since users started using their mobile devices to record videos. Maybe it is because I am in video production that it bothers me so much but you would think that everyone would want their videos to look good right?
It is very simple, think of your iPhone as a flatscreen (16×9) TV, would you turn it on it’s side to watch something? Remember that next time you are recording with your iPhone or any smart phone for that matter. Your videos will appear like this when watching on a TV or online.
This is what it looks like when a video is recorded when holding the iPhone horizontal
To avoid the black bars on the side of your video when playing it back always record your video on your mobile device horizontal.