Hi,
Unless you have very high speed camera with more than 1000 frames per second, I think the limiting factor is the framerate of the video file (or the capabilities of the capture device).
When you shoot with a regular camera at, say 50 fps, the time resolution is 20ms. Each image is separated from the next one by this ammount, and you cannot get more accurate than that. Every timing you do can only be a multiple of this fundamental unit.
In that regard, displaying hundredth of seconds is already sometimes misleading, as the time measurements are really only as accurate as the frame rate. (In an early version, the last unit of the timecode display was the number of frames, which is more right, but less useful).
We could display microseconds, nanoseconds, but it will not be more accurate, just more misleading in my opinion.
There are cameras with more than 1000 fps though, I don't remember if this is nicely supported (up to 999fps should definitely be ok). I don't think 10000 fps capable device can be used for timing people (outside photofinish hardware that is).