Hi FearlessMailbox
I think the example you have sent boots the devices at the same time, but this bootup time might be different for each device. I would recommend booting the devices like done here, but then use something like the timestamp syncing to make sure the different devices are in sync. Make sure to start recording only once the devices are already booted and are showing previews.
Oh nevermind, found one example here
Thanks,
Jaka