The increasing complexity of television broadcasting, has, over the decades, resulted in an increased variety of ways in which audio and video can be presented to the audience after experiencing different delays. This paper explores the factors that affect whether what is presented to the audience will appear to be correct. Experimental results of a study of the effect of videos spatial resolution are included. Several international organizations are working to solve technical difficulties that result in incorrect synchronisation of audio and video. A summary of their activities is included. The Audio Engineering Society Standards Committee has a project to standardize an objective measurement method, and a test signal and prototype measurement apparatus contributed to the project are described. This document is based on a paper that was published at the 125th Audio Engineering Society Convention, New York, October 2008. Some additional figures from the presentation that was made at the convention have been included as an appendix to the paper.