Previous research on sports commentary generation has primarily focused on describing major events in the match.However, real-world commentary often includes comments beyond what is visible in the video content, e.g., “Florentina has acquired him for 7 million euros.”For enhancing the viewing experience with such background information,we developed an audio commentary system for football matches that generates utterances with background information, as well as play-by-play commentary.Our system first extracts visual information, and determines whether it is an appropriate timing to produce an utterance.Then it decides which type of utterance to generate: play-by-play or background information. In the latter case, the system leverages external knowledge through retrieval-augmented generation.