Considering that last year the WHO said that healthy people don't need to wear masks, that seems ike a pretty stupid policy for YouTube to keep.
https://www.reuters.com/article/us-health-coronavirus-facema...
"The findings are consistent with previous research. Health experts have long said a mask provides only limited protection for the person wearing it, but can dramatically reduce the risk to others if the wearer is infected, even when showing no symptoms."
Whether or not someone is "healthy" is completely irrelevant when you count that last part, "even when showing no symptoms".
It's not good advice.