What does Mélechon say in this video from 1:14:36 to 1:14:40?
Mais il faut bien qu'il y ait un débat au PS !
Mélenchon is making fun of Macron and Hamon, suggesting they were belonging to the same political party, while the actual PS (Parti socialiste) primaries debate, won by Hamon, was over and Macron had left the PS since a couple of years and founded his own competing party (En Marche).
It's quite cocasse (quirky?) because Mélenchon followed exactly the same path a few years earlier when he founded the Parti de gauche.