I find it hard to believe that there are two separate clocks (timing down independently), and/or that they are not (automatically/always) synched, especially in a case where a ref says to put 9 seconds on the clock at the end. In other words, if both the scoreboard clock and the ref's clock show 8 seconds, and the refs then say to adjusted them to 9, is there any conceivable way they are not both at exactly 9 seconds?? Plus, given there is no decimal on any of the clocks, I don't think the scorekeeper could put 8.3 seconds on the clock, especially when told to put 9 on it, let alone putting 9.0 on one and 8.3 on the other. (The video by the HS scorekeeper explaining the types of clocks, etc, was interesting, and seems to refute the other kid's video purporting one of the clocks showing 9 seconds, but only really having 8.3 on it, based on how fast the clock went from 9 to 8 when the ball was snapped).
As a separate possibility to address, could the ref's clock be feeding the scoreboard clock? If so, the scoreboard clock would go to 0 either at the same time or maybe even a fraction of a second after the ref's clock went to 0, depending on if there are any lags between the two.
If someone finds a pic/video where the two clocks are shown at the same time, and the times are different, then that's another matter. (Which should be made impossible to ever happen).
I am also curious how the B1G video has two separate windows, side by side, one for the video of the play, and one separate and next to it, showing a clock. Is this actually what a ref would see on video review, or was this something put together after the fact with something like Photoshop?
EDIT: One of the commentators said a spike must take a minimum of 2 seconds, so if the scorekeepers clock shows fractional seconds, and we saw the start of the spike play to be at 11 seconds, but it was actually 10.57 seconds, then the scorekeeper should adjust the time to 8.57 seconds, which we would see as 9 flat. But per the kid who was a scorekeeper, it doesn't seem the UM clocks had fractional capabilities.