I use Handbrake, which is hosted in France...converts all my vids be it on PC or Mac. Two versions are available.
www.handbrake.fr. Free dude, it's free.
Vive la France!
Another one is ffmpeg, which needs a bit of installing on the Mac to run. You need to install the codecs separately but it works well. Google "ffmpeg" with OSX if you are keen.