brew install --use-clang --HEAD ffmpeg --with-faac --with-fdk-aac --with-ffplay --with-fontconfig --with-freetype --with-frei0r --with-libass --with-libbluray --with-libcaca --with-libquvi --with-libsoxr --with-libvidstab --with-libvorbis --with-libvpx --with-opencore-amr --with-openjpeg --with-openssl --with-opus --with-rtmpdump --with-speex --with-theora --with-tools --with-x265 --enable-libx264 --enable-gpl --enable-libxvid --enable-shared
--with-libvpx がないとWebM形式の動画を扱えないので注意
