How to avoid black side bars on video playback?

[shobuddy]

When I take video on my phone and play it back on a TV/monitor, I get black side bars. What do I need to do so playback is horizontal and the video takes up the whole screen (w/out sidebars)?

 

[dangus]

you need to shoot the video in the correct aspect ratio. if you're shooting in 4:3, for example, you will get black bars on a 16:9 monitor.