[solution] : need to install ffmpeg
Total 4 steps:
Step 1: sudo yum install ffmpeg ffmpeg-devel
Step 2: sudo rpm -v --import http://li.nux.ro/download/nux/RPM-GPG-KEY-nux.ro
Step 3: sudo rpm -Uvh http://li.nux.ro/download/nux/dextop/el7/x86_64/nux-dextop-release-0-5.el7.nux.noarch.rpm
Step4: sudo yum install ffmpeg ffmpeg-devel
标签：play,firefox,ffmpeg,nux,sudo,video,install,need From： https://www.cnblogs.com/clk100mhz/p/16652349.html