VMD 1.8.3 MacOS X Release Notes
The new MacOS X version of VMD is implemented using a native version of the FLTK GUI toolkit, Tcl/Tk and Python scripting, and Apple's OpenGL implementation. VMD requires MacOS X 10.2 or later.
In order to use features such as the 'vmdmovie' plugin, you would be well advised to install the "Fink" package manager, so that you can easily add related software such as the NetPBM image toolkit with simple commands such as "fink install netpbm".