The date is August 2014. Twitch.tv announces that they will soon remove all past broadcasts from their servers. But a team of rogue archivists saves over 100TB of videos to the Internet Archive. This site serves as an index for that archive (with 29146 videos from 1223 channels).
All the video data comes directly from the Internet Archive servers. You can help keep all this data available forever by making a donation to the Internet Archive.
Contact me with any issues or suggestions: Gonçalo Baltazar (firstname.lastname@example.org).