The ever growing explosion in technological advancements is paving the way to the expansion of multimedia applications. Unfortunately, current multimedia applications use centralized architectures. Before decentralized architectures are utilized and used, some issues related to decentralization must be addressed. In this paper, we focus on the problem of free riding in decentralized collaborative environments. We propose a novel taxonomy of free riders in multimedia systems based on trustworthiness. To the best of our knowledge, no existing literature considers trustworthiness, which we believe is a vital dimension that should be considered when identifying free riders. We also propose a new mechanism to filter out and isolate free riders. Our extensive simulation experiments show that our proposed algorithm is reasonably successful in identifying free riders in multimedia-based systems.