Good video, thanks for sharing. But...
"We recon if you drop one of these in the pool, everybody in the pool is probably dead"
Not sure if that is tongue in cheek, but if not, that is no-where near good enough. It's totally irresposible. You have at least 7 people on hand in case someone gets tangled in their dress etc - all sounds good, very sensible and good advice to those watching. But you basically say that if the person looking after the mains flash trips over, and knocks the flash into the water, everybody dies. Well lets hope they don't trip over.
You just need to check with a sparky - if that mains is RCD protected it should be ok (ie, you wouldn't kill anyone). If not, you can easily get an RCD protector to add to it.
But if you weren't being serious, no worries. Those trying to copy your work could do with some tips on how not to kill people with mains electricity.