We won't spoil the magic here, but according to a paper written by Netflix (PDF), it expects that by the end of 2016, most streams will be using TLS encryption. The company uses it for the same reason many sites (including Engadget) have switched to HTTPS by default: so that prying eyes on insecure connections might not be able to see what content you're viewing. Still, your workplace IT department may have its own MitM method so it's not necessarily foolproof, but it's a start, especially as governments and others may have interest in the data. The move also benefits Netflix, as it tries to keep third-party analytics from easily collecting detailed viewer data.