Gruss Betting Assistant allows 3rd party software to communicate with it using what is called a COM interface. It effectively becomes a server that allows other software to connect to it. Gruss Betting Assistant communicates with the Betfair Server through the Betfair API. TBM communicates with Gruss Betting Assistant through the COM server.
At no point does TBM communicate with Betfair. TBM simply tells Gruss Betting Assistant which selection to use, what odds to use, what stake to use and when to bet.