To try out the demo plugins:

Make a symlink called "playslave" to the provided plugin

"symlinkToThisDemoPluginUsingFilename_playslave"

and place the symlink in the same folder as the plugin
(i.e. $HOME/.precord/).

Similarly, make a symlink called "stopplayslave" to the provided plugin

"symlinkToThisDemoPluginUsingFilename_stopplayslave"

When you now run precord, you will find the (basically useless...) rxvt_date plugin demo app pops up when you press the play button and exits when you press the playstop button. To disable the demo simply delete the two symlinks you made.

For more information on how to write and/or use plugins, read the documentation READMEplugins.txt which is provided for download on the Precord murga forum thread.