Netflix's default Playback Setting speed is [AUTO] -- the service determines the amount of buffering along with the optimal streaming bitrate based on your current connection. If rebuffering occurs during playback, the settings adapt. Before I had an ATV, I found changing the default setting to [HIGH] cleared up any rebuffering, bitrate adjustments, and error messages. With this setting changed to [HIGH], there are occasionally a few seconds longer at the start for initial buffering, but with my 50/50 connection it rarely occurs. Also, when playback quality is set to [HIGH], the service still looks at your connection speed to determine the optimal amount of pre-buffering needed for interruption-free playback. If any rebuffering does occur, the buffer size is increased, but the streaming bitrate remains HD... It's a universal setting, so changing it in a web browser will also apply to the ATV app as well as any other method you use to access Netflix.