What I think is happening:
Plex believes the video, at least at the beginning, bursts over 200 Mbps.
This exceeds the limit of the Shield, so the video transcodes.
Look in the XML information for the file. On the line for the video stream it has requiredBandwidths="259715,213871,131062,99297,93493,89615,76656,71057. Those entries are in kbps.
I misread the log entry I mentioned above. It shows a limit of 200 Mbps (200000 kbps), not 20 Mbps.
Check the XML information for some of the other misbehaving videos in your system. See if they show similar values
I could not find any movies in my library with such high requiredbandwidths entries, so I cannot replicate using my Shield.
You’ll notice the requiredBandwidth entries in the XML file for the audio tracks are obviously incorrect (2147483647 = (2e+31) - 1):
requiredBandwidths="2147483647,2147483647,2147483647,2147483647,2147483647,2147483647,2147483647,366658
It is unclear if the incorrect audio analysis is a problem. I have some movies in my library with the same audio analysis, but the audio still direct plays.
