Nat Friedman, Github's CEO, personally joined the #youtube-dl IRC channel and initiated working towards the reinstatement of the project.
If the CEO personally taking a stand and working against this DMCA request, if the fact that all DMCA requests are publicly archived, if the fact that youtube-dl is already back up, do not convince you that GitHub had the right motives here, I don't know what to tell you.
If the CEO personally taking a stand and working against this DMCA request, if the fact that all DMCA requests are publicly archived, if the fact that youtube-dl is already back up, do not convince you that GitHub had the right motives here, I don't know what to tell you.