You can time to the second reasonably well if the artist is miming or doing live vocals on a prerecorded backing track. But the BBC thinking was the music works best on tv when it's cut with the music, though many cuts actually look best on the upbeat not the down. Imagine a shot of a drummer. You don't want to see the sticks already on the drum .. you want to cut to is just
before
the drummer brings the sticks down. Same with a guitar strum or a piano chord being played.
Well, indeed, and it was one reason why it was always noticeable when Top of the Pops used to show a performance from the German version - it was easy to spot them, not just because they were usually nu-metal acts (a genre especially popular in Germany) but the camerawork was very different, the camera used to be up the artists' nose and used to roam around all over the place.
Of course, good direction can really make a different to a performance. Tony Palmer's style on Twice a Fortnight in the sixties was hugely distinctive, and I absolutely love this performance, you wouldn't want this style of direction on everything but for this song it works brilliantly...
This doesn't have much to do with gameshows, so I'll just mention that I think the When X Goes Wrong series of clip shows are by far the weakest currently on TV, you can have good clip shows and bad ones, and these are bad ones. When we got more of Tommy Cooper dying than I've ever seen on TV, or ever wanted to see, on the Live TV one a few months back, that was it for me.