It is important for almost all users to know how their network environment can work correctly or suitably. Especially, it is considered to be significant whether really-provided (i.e. measured) performance is similar to theoretical one based on formulation or not. Sometimes the former performance may be rather different from the latter one from a viewpoint of our experience. We have utilized a kind of video transmission system which can be used as a network conference system. Not only because such a system becomes more and more useful in the distributed campus network environment, but also because the system must transmit certain amount of packet flows between and/or among its elements while it works. Such a video transmission system may be adequate and applicable to realize effective measurement of packet flow amount in the distributed campus network as a relatively wide experimental environment. This paper describes how to configure network conference scheme in order to formulate network performance and how to measure packet flow amount at specific points in the relevant network. A trial evaluation of network performance has been also carried out through comparison of packet flow amount for formulated (i.e theoretical) network performance and really measured one.