I found this 4.0 IPA and have tested it and it does work. Now I can't confirm it hasn't been tampered with in anyway so just FYI.
http://uploaded.net/file/32k1g1ne
The problem with this method while it does work, is that for me full quality ends up being 720x480. While with the latest version of netflix which results in the ISMA and ISMV files are very likely full 1080p from the file sizes at 100% quality.
The key method for the ISMV files is below. I can only find very little information about that keyformat but being that HLS streaming and ISMV/ISMA are pretty well known I imagine it has to be possible to decrypt the video in a similar fashion as the AES method. I'm not sure where the key might be stored though if it is on the iOS device at all.
#EXT-X-KEY:METHOD=ISO-23001-7,URI="+g=",KEYFORMAT="com.apple.streamingkeydeliv ery",KEYFORMATVERSIONS="1"