Some times you may get an error in FFMPEG Shared Libraries not Found while installing on your system,

checking whether to force gd support in ffmpeg-php... no
checking for ffmpeg headers... ...found in /usr/local/include/libavcodec
checking for ffmpeg
configure: error: ffmpeg shared libraries not found. Make sure ffmpeg is compiled as shared libraries using the --enable-shared option

Execute the below commands,
#  echo "/usr/local/lib" >> /etc/

#  echo "/usr/lib" >> /etc/

#  ldconfig