This came from an Italian website dedicated to the Ambrosian (Milanese) Latin Rite. I had no idea what it was all about so I enquired over at Catholic Answers Forums.
I am told: The flaming ball is lit during the feast of the patron saint and martyr. It is called ‘il faro” (the lighthouse???) It is a globe covered with a cotton fibers (decorated with cross, palms, and crown) and it is hung at the entrance of the presbiterium. It is the symbol of the life consumed by the love of Christ at the moment of martyrdom.