Millisecond stopwatch for visual stereo video synchronization measurement I am trying to get 2 video streams into sync at low cost. I would like to visually measure how good can I synchronize my cameras by pointing them to a millisecond capable stopwatch.

Does anyone know what is the refresh rate of an "old style" monochromatic LCD stopwatch (example)? I don't have one so I haven't tried to capture these yet. Wikipedia says an LCD could have a refresh rate as high as 200Hz. If LCD is slow, LED probably would be faster depending on circuity used.

So far I used online stopwatch, but these are limited by (usually) a 60Hz refresh rate of a computer LCD monitor. 60Hz lowers the resolution to about 16ms (1s/60Hz).
You can only sync video to an accuracy of a frame, or somewhere in the area of 15-40 mSec depending on frame rate. So as long as whatever you're shooting can update and refresh at least that quickly, it's not important to do much better. Even shooting a mechanical metronome will probably get you as close as anything else. The refresh rate of the display shouldn't be a factor, if you're examining both clips on the same screen.