The idea of the format is to spend a very little amount of time either creating a song or filking an existing song. This is not a new or unique concept, we all do this in one way or another. Musicians and writers have done this in varying forms forever.
The context for this particular format is for the SCA or re-enactment set. Songs or music set in or based around the re-enactment community.
As a competition for fun or reward this can be a fun format to set bards to. Have them create, then perform their works!