Yep. In the early 60’s my friend’s father told us the same thing.
I saw the video in the OP the other day because Adam Savage’s Tested channel is often recommended to me. It’s a mixture of weirdness and hopelessly nerdy.
I had that too! No idea what happened to it.
Do you remember where the flush water came from? Hand pumps? Ram effect of dynamic water pressure under sail?
Just curious. I assume the battleships I mentioned had a pump. And some low-level rating had to maintain the head plumbing.
Speaking of which, wonder where are the head(s) in NCC 1701?
Everywhere, just like now.
Now maybe they don’t have literal plumbing running between decks*, maybe they just use transporter tech (watch out for transporter malfunction-created evil poops!) but every cabin has one. The Franz Joseph blueprints even have a terlet off the bridge, because when ya gotta go, ya gotta go. (“Mr Chekov, that’s the third trip this hour. Is there a …problem?”)
*IMO Kirk-era starships have plumbing, and they reuse/recycle everything. Who knows what Picard-era ships do. They probably respect the autonomy of poop. 
eta: Now I’m thinking about alien waste disposal. Who knows what Klingon krap looks/smells like. Maybe it attacks plastic pipe. Do cat-like aliens need a litterbox? I’m reminded of Tom Selleck in Mr Baseball, and they asked him if he needed help in the toilet. He says “I know how to take a crap!” Then he gets a look at the Japanese hole in the floor thing, and goes “I need help taking a crap!” Starships could be like that.
How do you feel about people who misspell his name?
I always took that to be a more colloquial phrase, not necessarily suggesting that he was actually dead or lost as the ship broke up.
Does the Enterprise have a poop deck?
If such a person, and I doubt they exist, were to make a youtube video, expected to be watched by lots of people, did that, I would mock them mercilessly. And rightly so. On a message board? Only slight ribbing, a chastisement, maybe an upbraiding, and a warning to check before posting.
Honestly, I don’t know, I just figured it was just a hole in a board, like in an outhouse. When I found that pic my thought was, “I never knew they had water sluicing a chute. I wonder where it comes from.”
To be honest, when I heard as a kid that ships in the days of sail had toilets at the bow, I also assumed this was a hole leading directly to the ocean.
That’s one of the Stephen Biesty books, right? My son had a couple of those, and someone taking a dump is pretty much in every scene IIRC.
If you look carefully in the movie Master and Commander, during a brief, low shot showing the bow of HMS Surprise, you can see a sailor sitting as he relieves himself.