When Netflix loads a movie for instant play on your computer, it calculates the speed of your Internet connection and buffers the file appropriately. Sometimes only part of the movie will be buffered, slowing the playback time when you watch it. By adjusting the bitrate -- the rate at which the movie streams from the Netflix servers to your computer -- you can force the movie to play all the way through.
Go to the Netflix site and select a movie or television show for instant play. Click the "Play" button and wait for the page to load.
Left-click the black viewing area before the movie begins. Press Shift+B on your keyboard to bring up a bitrate options menu.
Move the slider to adjust the bitrate to a higher number than recommended and click "Okay." Press the "Play" button on your movie to see the new bitrate.
Try setting the cache options on your browser to allow up to 1G of cached information before adjusting the bitrate. Sometimes this will allow the film to buffer fully.
If you have a slow connection, manually adjusting the bitrate may decrease the overall quality of the movie you're streaming.