This expression, and its variants 'get it over the line,' and 'bring it across the line,' refer to achieving a goal, meeting a deadline, or completing a task successfully. It references the way a competitor must cross the finish line in order to complete a race. For that reason, the term 'bring it over the line' often implies great effort and difficulty, and something that was perhaps achieved by a narrow margin. As the video shows, this expression is much more common in a professional context rather than a social one, and is often used to express completing a deal or meeting a deadline. A phrase with a similar meaning is 'seal the deal.'