Convert MTS video to OGV (OGG) format via Terminal
It could be done with ffmpeg. First, install it with vorbis support:

brew install ffmpeg --with-libvpx --with-theora --with-libogg --with-libvorbis


After that, run command:

ffmpeg -i input_file.mts -acodec libvorbis -crf 21 -r 30000/1001 -deinterlace -vpre lossless_medium -y -threads 0 output_file.avi