It's almost never going to be that bad unless you're going out over a terrible internet connection. Worst case you could have a way to configure one camera to r

It's almost never going to be that bad unless you're going out over a terrible internet connection. Worst case you could have a way to configure one camera to run its own NTP server and have the others sync to it over LAN. That would get you sub-frame (<1ms) precision easily.