I noticed that similar issue was reported Re: Mageia 7. I tried unsuccessfully to solve it by myself after reading the various replies in that thread.
My system details:
Mageia8, Dual screen, Dual boot - windows 10 and Mageia 8, Cinnamon desktop.
I verified that both libx264 and libx265 are there
-rwxr-xr-x 1 root root 2266432 Jul 6 2020 /lib64/libx264.so.157*
-rwxr-xr-x 1 root root 4813216 Jul 12 2020 /lib64/libx265.so.192*
I'll appreciate your help
JJF