That "exclusive" file might come packed with a tracker. Once you run it, your IP address and device information can be used to target you for further scams.
Train to Busan is a visual and auditory spectacle. The terrifying silence before a zombie attack, the sweeping orchestral score, and the crisp visual effects of the zombie horde piling onto the train are all ruined in a 240p pirated copy with tinny audio. You aren't watching the movie; you are watching a ghost of it.
IsaiDub is not a charity. They make money via malicious pop-up ads. One wrong click on a "Download Now" button on the isaidub train to busan exclusive page will install: