There are many topics and article on the web about this, and yet they are either obsolete, or have contradicting info, or plainly don’t work.
Widevine is essential for playing DRM content, and yet it’s insanely hard to make it work.
In my case, I wanted to watch HBO GO through OSMC. I installed HGO EU plugin, logged in to my HBO GO account and when I played something, it asked me to install widevine. I said yes, it warned me that this is 1GB download because it’s extracted from Chrome OS image. Since I had no other choice, I confirmed, it downloaded and installed.
I can see widevinecmd.so in the system, so it looks all right. And yet when I want to watch some video, I see a loading sign, then the screen flickers and stops loading. No warning, error or anything. Simply, nothing is happening.
Am I missing something?
EDIT: I just installed the system update and now widevine is working 
Topic closed.