The Test Match Special team on BBC Radio are treated as very special people by all those who care about such things, but even they are not perfect. Sometimes, for instance, they don't know what's going on. You know they don't know what's going on because they say things like, "Well, I'm not quite sure what happened there," or "Well, I don't know if that was bat or pad or bat and pad," or "Was that a tickle there? Might well have been," and you can't blame them, because it's bad enough trying to keep an eye on the double-decker buses passing by or the seagulls flying around or the people watching from adjacent cranes without having to monitor the cricket as well.

Television is different. TV cricket broadcasts can go on for minutes on end without anyone saying anything, and when someone comes back in the commentary box and says something, the viewer can get quite a shock.

But on radio, what with the strain of describing buses and seagulls, reading out letters and laughing a lot, no wonder that commentators sometimes lose their grip on actuality. What generally happens is that one of the Test Match Special team says something like, "Well, let's have a look at that one again," which is a curious thing to say on radio, until you realise they are going to look at it again on TV. They are going to look at a slow-motion video replay on TV. The radio commentators are, in fact, watching the cricket match at which they are present on television.

We all accept this because everyone nowadays watches things on TV and expects instant replays. If you go to a live match after weeks of watching TV sport, you get a shock when a goal is scored or a wicket falls and there is no instant replay. Instant replays are now part of our lives, allowing us to relive the second-hand moment sprawled in front of the screen.

However, there is also a belief, fostered partly by the Test Match Special team, that if you see it again, you will see what really happened. This is absolutely untrue. Slow-motion replays make things no clearer at all. How often have we seen a disputed line call at Wimbledon shown in slow motion, and heard the commentators say, "Well, it seemed like a small cloud of chalk - it was certainly close to the line, but it was a hard one to call." How often have we seen a replay of a disputed rugby try and heard the commentator conclude that nobody could really say if it was grounded or not.

There was a good example during the last day's play of the late Test match, when one of the umpire's decisions depended on whether the ball had hit the batsman's bat or foot. The ball definitely hit something bang in front of the stumps and went flying off down the leg side. Everyone appealed. He was given out, lbw. This would have been a fair verdict if the ball had hit his foot, but quite unjust if it had gone off his bat. So we saw the incident again from different angles, in slow motion, and it was impossible to tell if it had hit the ball or the foot. One of the TV commentators said that he didn't think the ball would have gone off at that angle from a boot, which struck me as ridiculous. The plain simple fact was that the video replay made things no clearer at all.

About all you can say for the TV view of cricket is that it is slightly better than watching it in the flesh. Spectators at a cricket match must have very good eyesight to see what is going on at all. If you are sideways on to the match, you cannot even see a fast ball being bowled. You can see the bowler fling his arm, and you see the batsman react but you cannot see the ball at all. I have a friend called Nick who has a theory that it would be quite easy to play most of a Test match without a ball, as long as the players were competent at miming. The bowler would bowl an imaginary ball, the batsman would swipe viciously at thin air and a fielder would fling himself heroically into empty space, and it wouldn't look so very different from what goes on now.

So when it comes down to it, I can see only one use of the cricket TV slow-motion replay. It may not show you what happened to the ball, or whether it struck bat or pad, but it does prove that a cricket ball is actually being used.