I first heard this expression used on British television during coverage of a soccer game. Since that time I have heard it used only very rarely, but have seen many examples of the phenomenon that it describes, and most people who watch sports on TV will be familiar with it.
Commentator's curse can strike during any televised sporting event. Essentially, a commentator draws attention to a particular aspect of a game or a player, or makes a prediction based on past performance, and is immediately proven wrong by events.
Expect the commentator's curse to strike any time you hear a phrase such as "He never misses from there" (player misses from there), or "She's got such great balance and poise" (player falls over).