This clip is from the instructional video How to Get Your Film Into Film Festivals, and it highlights the surprise that many filmmakers get when they arrive at their second film festival.
While the principles of marketing are much the same everywhere, the specifics of how to reach an audience can be vastly different. Fortunately the festival staff is there to help you understand the rules and vibe of their event. Pay attention to the guidelines they give you and be sure to take advantage of any opportunities for press and marketing through official festival channels. Too often filmmakers figure they'll be lost in the shuffle or it can't be worth filling out those forms or whatever – don't fall into that trap. The rewards at any festival go to the people who show up and put in the effort.