Some people here are complaining that this is a hack, technical debt, etc. I thought the point would be the political one, as it were. YouTube.com gets special treatment in a major web browser, whereas Sal's discount video website has to conform to standards like all the other plebs.
It's an erosion (however minor, by itself) of the idea of an open standard.
Apple has a list of websites with quirks that don’t support its “generate strong passwords” feature even though there is HTML spec where you can specify the types of passwords you support.
https://github.com/apple/password-manager-resources
Many of these sites are quite obscure.