Kirk here. The video on the United Nations Environment Programme website that is mentioned in the article can be found at the second URL shown below. It has English subtitles.
https://mainichi.jp/english/articles/20211111/p2a/00m/0na/022000c
https://www.unep.org/globalmercurypartnership/news/video/mercury-and-minamata-disease-lesson-japan
Japan citizens' group makes video on Minamata patients to promote mercury regulation - The Mainichi
MINAMATA, Kumamoto -- A 13-minute video on the daily lives of Minamata disease patients, produced by a citizens' group in this southwestern Japan city