Why do I get a thick grey color border after I publish my file in a video format?

Hi Vishal, 

If it's not related to shape outlines, would you mind sharing a copy of your project file here so we can take a look at what's causing the lines to appear? We'll delete them as soon as we're done troubleshooting. You can also open a case with our support team if you prefer to share your project file in private.