From the video description:

“We interviewed one of Noctua’s technical team members (Jakob Dellinger) to discuss the challenges and troubles of focusing entirely on performance for a cooling product. This video goes over fan behaviors like tensile strength, endurance, aging, creep, and cooling characteristics like blade tip distance from the frame and blade passing harmonics. The video is a surprisingly transparent insight into what Noctua has been dealing with for 8 years now as it has attempted to reinvent its most popular product, and the company now thinks it has an NH-D15 Gen2 and “Next Gen Fan” nearly ready for primetime.”