I wonder if they have done a cost analysis on moving their content distribution to BitTorrent :)
On a serious note, it’s surprising how much data you can push through with the servers nowadays. Such bandwidth isn’t something that many will see and it’s mind-boggling for me that all of that can be generated from a single server.
I doubt they’d get the latency that they need. They’ve given some talks about these things at FreeBSD DevSummits. Apparently a lot of Netflix accesses involve seeking through video streams. They put a lot of effort into making sure that when you jump to 47 minutes and 12 seconds into the video, it loads the next bit of video and plays quickly enough that no one sits waiting and becoming unhappy. With BitTorrent, you might be able to get the streaming bandwidth, but getting the latency would be incredibly hard.
It’s also worth noting that a lot of Netflix customers are on mobile devices these days and would probably be annoyed about having to upload streams to other customers. Bandwidth in datacenters (particularly when you’re peering with ISPs so that their customers get fast Netflix) is very cheap for Netflix, much cheaper than upstream bandwidth for most of their customers.
Evidently, according to BitTorrent.com, they already do use BitTorrent for something. Anyway, NetFlix’s OpenConnect is an interesting program: openconnect.netflix.com and also BitTorrent is used for live streaming: https://www.bittorrent.com/products/live-streaming/dlive/