Adding black bars to a video, also known as letterboxing, can improve the cinematic look of the video by framing the content in a way that is consistent with the aspect ratio of traditional film.

The aspect ratio of traditional film is typically wider than the aspect ratio of modern high-definition video, which means that when you watch a film on a TV or monitor, black bars will appear at the top and bottom of the screen to fill in the extra space. This helps to preserve the original aspect ratio of the film and ensures that none of the content is cut off or distorted.

By adding black bars to your video, you can create a similar cinematic look that is consistent with the aspect ratio of traditional film. This can help to give your video a more professional and polished appearance, and can also help to draw the viewer's attention to the center of the screen where the main action is taking place.

In addition to improving the aesthetic appeal of your video, adding black bars can also be useful for preserving the original aspect ratio of your content, particularly if you are working with footage that has been shot in a different aspect ratio. By letterboxing the footage, you can ensure that none of the important visual information is lost or distorted.