I watched a video that uses gravity to boil water just by lifting it and lowering the pressure. explanation is better in this video

https://www.youtube.com/watch?v=hHNoHhbfFDQ

so I’m running the scenario through my head of lifting the bottle to the point of “cold” boil then lowering it down (while keeping the hose above boil level to avoid contamination from the original) and I’m trying to figure out what the issue would be.

would the water vapor never condense until a temperature change happened, would it be too slow at distilling since there can only be as much water vapor can only be as much as the container?

what are the flaws or limitations