While I don't disagree with Stallman, how would that solve this problem? This is about a major video hosting platform having market shares and injecting ads into their streams / UI.
I do not see - even if every line of youtube's software sources were public - how that would solve the issue that the hosting platform can insert ads anywhere - honestly, as much as I hate ads, I can't even blame youtube for doing something morally questionable - they are providing a service, they are not a public institution obligated to making information accessible.