Wow. Take a look at this...

[SamG]

If you can transmit and receive from a satellite in <.25 (1/4 second), and the distance is 45,000 miles to make that trip (22,500 one way), I highly doubt even 2000 feet of cable is going to "slow down" a picture.

Here's the other thing to think about... as long as the camera shooting the action and the camera shooting the clock are both "delayed" (right, that's what you're saying, that the cable distance affects speed), then they're still in sync.

They could both be delayed 10 seconds, but as long as they're in sync they're accurate.

And another thought... broadcasts (from college to pro) are used all the time to review last second shots. They use the same technology that was shown in the reply (game/shot clock superimposed over game camera). If the system is inaccurate, why use it?