If the Moodbar executable tells you that it can't find an element — i.e., it gives an error message like Could not create element of type fftwspectrum, please install it.
— that usually means that you either don't have the required plugins installed (see the plugin list here), or that you didn't install the Moodbar package in the same prefix as GStreamer. If libmoodbar.so and libgstdecodebin.so are not in the same directory, then Moodbar is not installed in the same prefix as GStreamer. Please read the INSTALL file for instructions on how to configure the moodbar package correctly. Alternatively, if you know what you're doing, it may be easier for you to take a look at the GST_PLUGIN_PATH environment variable.