Originally Posted by midwestmac
You have to install libass-dev and also you don't need to enable --mt now as ffmpeg-mt has since merged into the main trunk. you don't need to delete anything.
BTW. if you are installing from git you don't need to download the tarball. If you look into the mplayer2-build folder after finish running
you would find a readme file which tells you the step to build mplayer2 and the dependencies.
git clone git://git.mplayer2.org/mplayer2-build.git
An easier way to install mplayer2 is to add the MOTU ppa and install it from the package manager. I believe mplayer from MOTU also works in Lubuntu 12.04 (don't know that there is a problem because I never install mplayer from the default repo, it is always hopelessly out of date)
mplayer/mplayer2 has a nice gui frontend called SMplayer, you can get the latest version by adding the developer's ppa
EDITED: If you install from ppa you'll get update automatically. If you install it locally by compiling yourself (the command "echo --prefix=$HOME" instructs that mplayer2 be installed in /home/usrname/bin) you need to update manually once in a while. This is how, from the terminal
mv mplayer mplayer2