Interesting idea, although the clean water part is debatable - since the water wasn’t boiled, bacteria still remain in the stilled water. This technique should only work on a sunny day and only as a supplement for other sources of water.
I think he’s referring to the sheets of transparent plastic that can be used to condense water from the air which to my knowledge may not be pure, but it’s clean enough to drink. Assuming of course your plastic and storage container are clean and the air isn’t “I need a filter mask at least once a week to safely breathe” polluted.