Medieval Hardhat Diving Suit?

Factual Questions
1

In surfing Youtube, I came across this little gem:

Very strange? No info was given about the clip-but as you can see, the diver was fed air through a leather? hose, from a bellows.
Given the low pressure capabilities of the bellows, how deep could the diver descend?
I assume this stunt was done to test a theory…but as far as I know, the hardhat diving suit was invented by Augustus Siebe , around 1805.
From the dress of these participnts, it looks like the period was around AD 1300 or so-do we have any record of such diving apparatus from that period?

2

That is from a TV pseudodocumentary on last year or year before, one of these ‘ancient engineering’ type shows where they take mentions of tech, or random little marginalia drawings from DaVinci’s notebooks and try to build them to ‘prove’ they could have been done back then with the tech they had available. Sometimes they also claim that they did make them but we never found any archeological evidence and nonsense like that.