I have already installed libav-tools. I purged it and reinstalled. When I run ffmpeg it says not found and suggests to install libav-tools. When I try that it says it is the newest version.
If you wish to use a newish version of ffmpeg in 12.04 then your best bet would be to use a static version available here. http://johnvansickle.com/ffmpeg/
Make sure your kernel is new enough. (should be..
Try installing the ffmpeg package
sudo apt-get install ffmpeg, which includes all the libav libs and also libav-tools according to the [package details] info.(https://launchpad.net/ubuntu/+source/ffmpeg).