The reason I chose a Chromecast is because it means less action from the moment you decide to watch a movie, and the moment you’re watching it. I found it really useful to sit on my sofa, open Plex on my smatphone, and that’s it, all my movies ready to be played. No other box, no other interface, no other remote as you could have with a Nvidia Shield, Zidoo, or a mini PC as an HTPC.
About the post you mentioned, it’s saying that you can’t direct stream a 4K video from Plex to a CC Ultra. As I don’t have any 4k video, I couldn’t verify. But that’s good to know. I wonder if a My Cloud PR*100 could transcode a 4k HEVC. I’d say it couldn’t lol.
But what I was saying, is that you can’t direct stream a 1080p HEVC video to a CC Ultra out of the box. You’ll need to change the chromecast profile (ie chromecast.xml) on your Plex Media Server. And the topic also provide a chromecast profile. I think there is many chromecast profiles (all working) on internet, created by some guys who had run into this issue.