Who decided Corbyn was "unelectable"?

https://www.youtube.com/watch?v=8os-nKuoM3o&feature=youtu.be

Robbo sez, "Jonathan Pie, preeminent UK political satirist, takes on British media and their role in declaring newly re-elected Labour Party leader Jeremy Corbyn 'unelectable'. Pie destroys the outrageous un-democratic media bias that has hounded Corbyn throughout his time as Labour leader and does so with his usual outstanding, hilarious, enraged and profane style."