How to play a westley file

I forgot ... the command line utility bundled with MLT.

The MLT command line player is inigo.

You can play or render a .westley or .kdenlive file with it. To play it:
inigo my_playlist.westley

to render it:
inigo my_playlist.westley -consumer avformat:rendered_file.mpg real_time=0 [then add ffmpeg 's avformat specific parameters]