This is one Hell of a bizarre sounding language. I guess it sounds more like French than anything else, but it doesn’t sound much like French either! It doesn’t sound like much of anything!
Truth is, they are actually speaking and singing German in this video, as bizarre as that sounds. Yes, this is actually German. German with a very heavy French influence, but German nevertheless. It’s Moselle Franconian, a middle Franconian language in this case spoken in France in Sarreguemines right on the German border. It’s probably intelligible with other Moselle Franconian languages spoken over the border. I have heard that Germans visiting the city of Trier say that the Moselle Franconian spoken there might as well be Chinese!
These are Middle German languages that developed off the same tree – Franconian – that went to Dutch. The Low Franconian languages went to various forms of Dutch, and the Middle Franconian languages went to German. The Luxembourgish spoken in Luxembourg sounds something like this.