If I know the weight of each speaker, light and video wall, is that data not sufficient to prevent overload?

Unfortunately not. The problem lies not just in the total weight of the suspended load but in the load distribution: Each time there are more than two hoists on a truss or more than three hoists in a structure, it becomes statically indeterminate, resulting in unpredictable load distribution. In most cases this will cause a load imbalance, in which some of the hoists may reach overload while others carry only a small part of the load. This is a highly undesirable situation that can result in dangerous overload.