An example of where video and referees connect

Once upon a time back in 1979 or so, the University of New Orleans Privateer men's basketball team played (I think) Dayton at the "Chamber of Horrors," the gym on the main campus. (This was years before the Lakefront Arena was constructed). One of the Dayton guards was engaging in a lot of off-the-ball harassment of one of the UNO guards. At one point near the end of the game (UNO was winning handily at the time), the UNO guard had enough of the other guy's antics. The referees were both down-court, the two guards closer to center court. The UNO guard goes to tie his shoe and the Dayton guy stands right behind him, just to piss him off. Next thing you know, the Dayton guard is on the ground after having been clocked by an elbow to the chin as the UNO guard stood up.

The Dayton coach and bench went nuts, with the coach threatening to beat the crap out of the UNO player. There was little the referees could do, because the the Dayton player was literally crawling up the UNO guy's butt. The guy had no business being that close to the UNO player, and neither of them saw the actual contact to determine if it was deliberate.

Fast-forward to last Saturday. A football pitch is pretty big, and there's a lot of things that three officials often don't see. English Premier Leagues are well-recorded, however, much to the chagrin of Arsenal's Alexander Hleb:

The FA has taken action after reviewing video evidence of an incident
involving Hleb and Reading's Graeme Murty in a game Arsenal won 2-0
last Saturday.

"The incident was not seen by referee Peter Walton," said an FA statement.
"Having now watched video footage, Walton has informed the FA
that, had he seen it, he would have shown Hleb a red card for violent
conduct."

Hleb forgot that he wasn't at an amateur men's league game at some playground on Sunday morning, and now it's going to cut his season short early.