It could have been Eskuara, the Basque language which is widely spoken (even aggressively spoken!) or Catalan or any of the other local dialects of French and Spanish, even some Castilian pronunciations on the Mediterranean side. Also there seemed so much sharing of vocabulary between these languages and English, German etc., I was mystified.
Based on shifts in intonation and audience I could hear the shopkeepers switch between languages as naturally as blinking. The people here didn’t look like they had particularly big heads but their language-brains must have developed very early and Very Large.
This guy is pure definitive Basque.