HEVC/H265 videos not playing in SM Player
SMPlayer by default uses mplayer executable as its backend. You would need it to use mpv player instead.
Install mpv player first.
sudo apt-get install mpv
Then open SMPlayer and go to its options. Change the location in Mplayer/mpv executable to
/usr/bin/mpv
That should fix it. Make sure you have SMPlayer 15.9 installed.