Netflix works best when streaming Netflix movies from an internet connection with a minimum download speed of 3 Mbps but I've streamed Netflix movies before when my download speed dropped to 2 Mbps and although there was a little bit of buffering the movie didn't buffer that often.
But if you want a great experience streaming Netflix movies you should have a internet download speed of 3 Mbps at least and of course the faster download speed the better especially if multiple people are streaming Netflix in your household.