A method carried-out by a client media receiver , the method comprising: launching a streaming media interface application in response to user input received at the client media receiver; substantially concurrently with launching, transmitting a request over a communications network to a streaming media server for a sample video stream ; when receiving the sample video stream from the streaming media server, playing the sample video stream on the client media receiver ; in an ABR pretesting process, continuing sample video playback with Adaptive Bit Rate (ABR) variations in streaming the sample video from the streaming media server until user input is received requesting streaming of user-selected content stream to the client media receiver; then, in response to the user input requesting streaming of user-selected content stream to the client media receiver, terminating playback of the sample video and determining an optimized Adaptive Bit Rate (ABR) setting under current network conditions based upon a recent ABR value of the sample video stream, wherein the optimized ABR setting obtained via the ABR pretesting process is dependent on factors including current latency for content key retrieval and decryption of segments of the video stream, the time required for decoding and consideration of processing tasks of the receiver for maintaining appropriate forward buffer duration for preventing potential future stalls; transmitting a request to the streaming media server for the user-selected content stream at the optimized ABR setting; and presenting the user-selected content stream, when received from the streaming media server, on a display device associated with the client media receiver . launching a streaming media interface application in response to user input received at the client media receiver; substantially concurrently with launching, transmitting a request over a communications network to a streaming media server for a sample video stream ; when receiving the sample video stream from the streaming media server, playing the sample video stream on the client media receiver ; in an ABR pretesting process, continuing sample video playback with Adaptive Bit Rate (ABR) variations in streaming the sample video from the streaming media server until user input is received requesting streaming of user-selected content stream to the client media receiver; then, in response to the user input requesting streaming of user-selected content stream to the client media receiver, terminating playback of the sample video and determining an optimized Adaptive Bit Rate (ABR) setting under current network conditions based upon a recent ABR value of the sample video stream, wherein the optimized ABR setting obtained via the ABR pretesting process is dependent on factors including current latency for content key retrieval and decryption of segments of the video stream, the time required for decoding and consideration of processing tasks of the receiver for maintaining appropriate forward buffer duration for preventing potential future stalls; transmitting a request to the streaming media server for the user-selected content stream at the optimized ABR setting; and presenting the user-selected content stream, when received from the streaming media server, on a display device associated with the client media receiver . <EOS>