A streaming media assessment system comprises assessment servers, media clients, data collection points, helper agents, and report servers. An assessment tool is downloaded or otherwise installed on an end-user client machine and associated with its media player. An assessment server is in communication with the assessment tool over the network and can send control messages to conduct tests and gather information from the assessment tool. The client machine media player is controlled to stop and start by the assessment tool and it will provide measurements that can be forwarded to the assessment servers. Analyses are then produced by the assessment servers of the actual media streams that were received by many such client machine media players. The report servers issue various formatted reports for the system's sponsors and subscribers.