Aren't team news, injuries, and other match details usually openly available on the internet and through sports bookies for gamblers to use when placing bets?. Also, do these officials typically place their bets through sports bookies or among themselves?
I don’t think they’re talking about being up to date with public information being insider information. More likely they mean people who know things that aren’t made public. Maybe a player told you he’s going to throw the game and make his team lose. Betting with that information would be considered insider gambling and is not very common.