Assuming one has homebrew installed:

$ brew update && brew upgrade
$ brew install ffmpeg --with-fdk-aac --with-ffplay --with-freetype --with-frei0r --with-libass --with-libvo-aacenc --with-libvorbis --with-libvpx --with-opencore-amr --with-openjpeg --with-opus --with-rtmpdump --with-schroedinger --with-speex --with-theora --with-tools
$ cd ~/dropbox
$ for video in *.MOV; do ffmpeg -i "$video" -vcodec h264 -acodec aac -strict -2 "${video%.*}.mp4" ; done
$ rm *.MOV