Content-modification system with transmission delay-based feature

In one aspect, a method includes receiving query fingerprint data representing content received by a content-presentation device. The method also includes determining a content-transmission delay between a content-distribution system and the content-presentation device. The method also includes using at least the determined content-transmission delay as a basis to select, from among a plurality of reference fingerprint data sets, a reference fingerprint data set that corresponds with the determined content-transmission delay. The method also includes detecting a match between the query fingerprint data and at least a portion of reference fingerprint data in the selected reference fingerprint data set. The method also includes responsive to detecting the match, performing an action.