Solid math and reasonable general principles, with an element or two I question. He comes close to clarifying it, though not quite. And while the percentage of 50 was a disposable placeholder to illustrate valid points, I doubt cotton could be quite so effective as 50% leading to 75% (and certainly not 100%) and some assumptions are required to flow along with the logic, as was mentioned. This is still reasonable for a fast-paced video; some finicky details must be overlooked. However, it is primarily based on math and no data was shown giving any unambiguous indication for cotton efficacy. Also, he addresses directionality as nearly equal for the illustration, but later provides another resource that accounts for it in detail. Was this prefactored? Otherwise surprisingly apropos and worthwhile.

Thank you