It was not DOA when they first started using it -- it was better than the streaming technology available via Flash at the time - and also the only one with DRM that would meet the the qualifications of the media companies that they license their content from. I don't think Netflix wants DRM any more than the majority of us, but they don't really have a choice to offer such content.
Netflix is using a lot of open source software: Linux, Cassandra, Zookeeper, Java, etc.
And then they sign a sleazy backroom deal with Microsoft and only support silverlight, which is a technology dead on arrival. I don't get it.