With some ingenuity and a command prompt, this single line samplet can be converted / expanded into any timer of any length:
now & wait 01 & ECHO ^G (^G) & now & wait 01 & wait -m 250 & ECHO ^G (^G) & wait -m 750 & ECHO ^G (^G) & now
The single line sample uses native* Windows commands wait.exe (sometimes named sleep.exe and usually included in every consumer version of Windows but always available free in the 11mb 2003 Microsoft Resource kit http://www.microsoft.com/en-us/download/details.aspx?id=17657
(Alt + NumberPad 7 or visit ss64.com for a pristine copyable instruciton)
to produce one of your systems default tone
The final wait -m parameter is milliseconds since you inquired about fractional seconds and the example is a quarter sec.
Wait (sleep.exe) syntax:
sleep /?
Usage: sleep time-to-sleep-in-seconds
sleep [-m] time-to-sleep-in-milliseconds
sleep [-c] commited-memory ratio (1%-100%)
Using goto parameters and breaking the example into separate lines even using for/if statements gives you more possibilites than required.
But, for a really fast ready to run online stopwatch also usable when a connection isn't feasbile, there is online-stopwatch.com with ready to go flashlets
I'm leery of using a video on the same windows system performing video editing until it was tuned and file indexing was disabled or at least reconfigured to avoid running during idle periods since the latency could even impact a metronome sync video.