Has Netflix done anything to make sure the test results are not skewed by the type of content being streamed? A lot of their content is not available in HD, and I doubt these SD programs even approach 2 Mbps in streaming quality. If a bunch of low quality cartoons are being streamed, it might lower the overall results when compared to a higher quality HD action movie.
Clearly the overall results are nearly identical where subscriber numbers are reasonably equal, or at least above a certain threshold, but Google would have a significantly lower number of subscribers. Perhaps if Google had 100,000 subscribers then they too would be around 2 Mbps along with the rest of the crowd, due mostly to the type of content being streamed, and not necessarily the quality of the connection?
Edit: I'm seeing references to much lower MAXIMUM streaming for HD content.
Netflix streams HD content using Microsoft VC1AP encoding at a maximum bitrate of between 2600 kbit/s and 3800 kbit/s (depending on the movie). A lower bitrate feed may be supplied if the user's network connection is not capable of handling the maximum bitrate available for the film in question.
Netflix recommends that people stream its movies over a broadband connection with a speed of at least 1.5 megabits per second (1.5 Mbit/s), and that people use an Internet connection of at least 3 megabits per second to get better-looking video on par with a DVD.
Netflix provides users the ability to choose their download rates / quality of video on their site (»account.netflix.com/VideoQuality ··· uality)"