It just shows HD logo beside the title but it actually doesn't work. If anything doesn't work on least copyrighted test patterns - it won't work on anything in Netflux. I also tried this on my unofficial Android box which has Widevine L1 but also fails and caps the video at 480p. The mod is just to enable the l9go besides the title
Good news guys the mi team gonna release Widevine L1 support to our beloved F1 in the upcoming beta within Q4
Source: http://en.miui.com/thread-4272498-1-1.html