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

Hi Vishal,

Have you tried removing the shape outline of the video object? You can take a look at my response here where I detailed how the shape outlines of objects can be removed.

• Slight off white border - inside edge of Storyline 360 Player

If this doesn't work, would you be willing to share a copy of your project file here so I can test your file and see how the outline in your screenshot can be removed?