It was happening with me recently for some of the videos which I edited in the live movie maker and exported to be later uploaded on the youtube channel. I saw the black lines above and below the video once I uploaded them to the youtube channel page, I noticed these black lines in the final video not only above and below, but also on both right and left side of the video after that video was playing on youtube after the upload.
This could happen to any one who uses live movie maker for basic or advanced video editing, as by default movie maker has such settings in that these black lines or thick black border will appear on all the videos produced. Some of the live movie maker users suspected that the final format of the video which gets exported out of movie maker is responsible for this but this is not the case.
Change Aspect Ratio In Live Movie Maker Project
In order to remove these black bars from top, bottom and from right and left sides from the final produced video, you need to change the aspect ratio of the video from 4:3 to 16:9, aspect ratio settings are available under project tab in live movie maker.
You just need to select the widescreen aspect ratio and then click save button to save changes in your live movie maker template and once you do this all the video exported will not have any black bars above and below or on the right or left side of the final video exported out of the project.
Please Note: The aspect ratio settings could be located in different way if you are using old version live movie maker.
The above procedure to fix the black bars in the video, but you If it does not or you have a specific problem related to this one, please let us know through the comment section below.