We consider the problem of streaming multi-user videos over the downlink of a Cognitive Radio Network (CRN), where each Cognitive User (CU) can access one channel at a time. Motivated by the prior work that establishes a separation principle for the joint design of spectrum sensor, sensing, and access polices, we first model cooperative spectrum sensing as an Integer Programming problem (IP) and develop a Greedy Poly-matching scheme to solve it for the optimal sensing strategies. We then formulate the problem of CU Quality of Experience (QoE) maximization as a maximum weight matching problem and solve it with the Hungarian Method for optimal channel assignments. The proposed spectrum sensing and channel assignment algorithms are compared with benchmark schemes in simulations, and are found to outperform the benchmark schemes in terms of available channels discovered and CU QoE achieved.