
developers.google.com/youtube/iframe_api_reference
You might not need actually that, as you can pass a start time to their html embed script.
You'd have to write a script to calculate how many seconds someone is after the start time, so you can pass that to it.
I think this does most of that.
( , Mon 8 Jul 2019, 9:19, Reply)

I'll definitely set this up if I can convince anyone to pay for extra hours
( , Mon 8 Jul 2019, 23:55, Reply)