Major speeches are distributed to press in advance under embargo — the State of the Union, central bank testimony, keynote addresses — and 'as prepared for delivery' text circulates among credentialed journalists before a word is spoken. Where that text is legitimately available, a mention market is not a prediction at all; it is a text search. The edge is knowing which events publish prepared remarks and which are improvised, where the base rate is all you have.
Markets on Polymarket where prepared-remarks embargo copy is the natural play: