```Any User-Generated Content you post publicly, including issues, comments, and contributions to other Users' repositories, may be viewed by others. By setting your repositories to be viewed publicly, you agree to allow others to view and "fork" your repositories (this means that others may make their own copies of Content from your repositories in repositories they control).```

Section D.5

Whoever the user that is posting the content is agreeing to the terms of service. If they don't actually have permission to agree to those terms with the content, then where that liability falls will likely fall to a court, but I'm sure I would argue as a user who forked the content, that I was given permission via the TOS which has to be followed by the user posting the content.

Because Winamp agreed to the ToS of GitHub by uploading their code to GitHub.

Doesn't that just mean that Github should be mad at them? Doesn't seem obvious that it actually gives me a license to do anything.

Pretty much all open source projects on GitHub rely on section D.6 of GitHub TOS (when you submit PR, it's licensed under project license and you have a right to do so).

TOS are not just fluff and paper, but legally binding. Granted, when there is a conflict between two conflicting requirements, it's never clear cut, but it's not just "GitHub will be mad."

Any project I've been involved in has its own explicit license, that allows such things (really allows much more, I don't touch anything closed source).

Is the ToS a contract? Even if it is would the remedy to Winamp breaking it be modifying the license Winamp provides?

Yes, every ToS is a contract. As for the most appropriate remedy, that's for a court to decide.

A repo's license doesn't overrule GitHub's policy.

The implication of this is not what you think. Basically github can go after Winamp and say they violated GitHub terms that is it. Just because winamp violated GitHubs terms of service does not mean they lose their copyright rights

Seems a lot like that would be the other way around, copyright law overrules random company's policy.