Methods and apparatus to measure flow of a drilling fluid composition include a test housing including a test matrix located between an inlet and an outlet, a test valve connected between the inlet of the test housing and a fluid reservoir, and a pressure assembly configured to apply pressure to drilling fluid contained in the fluid reservoir. According to one technique, a DVR receives, from a parent, identities of content items that the parent does not want children to view. Each slave device control other slave devices in a piconet without being aware of other slave devices except the master device.