I know every single step of this walk. This is my hometown and the reality of this journey is much much better, that the video. Trnava is a beautiful city and u have to visit it!
Try a morning bus from Bratislava to Smolenice, village of lovely nature and an unique castle. Then get a train to Trnava and stay there overnight. And you are back to B´lava next day. Nice and handy triangle of western Slovakia.