I have resorted to installing a snap for viber-unofficial. It works and solves the library problems (and the repackaging trick no longer yields a working viber). That is why snap was invented (or at least one reason)
However, there is still one problem. It needs permission to use the webcam. The askubuntu says you just give it permission. How to do that? They used the software center but that application is not available for ubuntu mate using the apt command.
The software boutique does not list the snap I installed.
What you need to is install Gnome Software. You can install it through the Software Boutique by clicking on the "More Software" icon at the top (it looks like an arrow pointing down on some sort of panel). If you prefer to install it via apt:
sudo apt install gnome-software
After you install gnome software, just search for viber-unofficial and click on it. Then just click on the permissions button and enable the webcam. Here are some screenshots to make things easier for you.
I noticed this morning in the viber permissions that the webcam permission switched itself off by itself. This is clearly some sort of bug. I've logged a bug report with the app developer.
Thanks for posting this command line method! Hopefully, Martin and the dev team will incorporate snap permissions into the next major version of software boutique and then we won't have to bother with the command line anymore to activate snap permissions properly!
The snap-store is now available as a snap and can set permissions.. This is specifically for poor schleps like us who don't have a snap integrated store. sudo snap install snap-store
Thanks for the info! Just installed the snap store and the permissions work great! Hopefully Canonical implements all the stuff they said that they wanted to implement in the snap store so it becomes a proper app store.
