While that may be true, I'd really like a better source than a channel which otherwise deals with "supplements that lengthen telomeres" or the age-old sauna-detox myth.
See the references below from The Journal of the American Medical Association (JAMA), The New England Journal of Medicine (NEJM), and Dr. Patrick who has interviewed the original researcher.
[1] https://media.jamanetwork.com/news-item/sauna-use-associated...
[2] https://www.jwatch.org/fw109897/2015/02/24/sauna-use-linked-...
[3] https://www.foundmyfitness.com/episodes/sauna-heart-presenta...
Then they point to two studies that show that Omega 3 and Vitamin D lenghtened or maintained telomere length against control groups.
The benefits of sauna are supported in a similar fashion.
You can argue that the studies are of poor quality, but that is true for most studies regarding medicine and especially nutrition. You gotta take a chance either way.