OK! I've made some discoveries. Inside your /Extra folder, there is the com.apple.Boot.plist file, and you are supposed to have the following lines:
<key>EthernetBuiltIn</key>
<string>Yes</string>
But it still wasn't working for me. It turns out, other entries in the file can keep this from working. In my case, I had entered my Graphics string so that the boot-up logo would be at a higher resolution. THIS was my problem. Once I deleted the entry, Netflix worked fine. So if you're using that long EFI string, try dumping it. I even kept the following line and the higher resolution still worked:
<key>Graphics Mode</key>
<string>1600x1200x32</string>
So again, trying simplifying your Boot.plist file, or reinstall it with Multibeast. The following is my exact Boot.plist. Good luck!
------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Kernel</key>
<string>mach_kernel</string>
<key>Kernel Flags</key>
<string>GraphicsEnabler=Yes</string>
<key>Timeout</key>
<string>1</string>
<key>Legacy Logo</key>
<string>Yes</string>
<key>Graphics Mode</key>
<string>1600x1200x32</string>
<key>EthernetBuiltIn</key>
<string>Yes</string>
</dict>
</plist>