MIDI output from WIDI VST Plugin can be routed differently depending on your software or hardware configuration.
There are three targets for MIDI output, they can be used simultaneously -VST Host, MIDI Out Device and built-in MIDI recorder.
VST host MIDI output means that the plugin tries to send MIDI messages directly to the host, and you can use WIDI VST Plugin as an input for a MIDI track or MIDI bus. In general, this is preferable way of getting MIDI data, but only some hosts support MIDI input from a plugin. You may get an additional hint whether your host support MIDI events or not on the Options page of the plugin. In case you cannot get any MIDI data using this type of output, you should use MIDI Out or record MIDI with a built-in MIDI recorder instead.
MIDI Out Device
In this mode the plugin attempts to output MIDI messages to your system MIDI Out Device. The device selected should not be open by any other application, including the VST host itself. You can use third-party phantom MIDI devices (Virtual MIDI Cables) to route MIDI data back to the host. There are some free ones available on the Internet.
Under MacOS X you may use Apple's original IAC driver to perform routing. To do this, choose "IAC driver" as MIDI out device in WIDI VST and choose IAC as input and output device in your VST host program. If you use this option, MIDI messages will route from WIDI VST back to VST host through IAC driver.
The plugin allows to record MIDI with the help of the built-in MIDI recorder. MIDI file recording starts after pressing Record button on the main page of the plugin and stops on pressing Stop. In order to save recorded MIDI data to a file press Save and enter the file name.