Kind of sad how the accent of the young man speaking in the beginning shows how much the "standard" northern French has marginalised the indigenous Occitan accents in French: his pronunciation in Occitan shows that standard Northern French is very much his first language and the phonology of Occitan is something he has not managed to master.
Much of Se Canta is probably understandable to Catalan speakers, especially those who speak or are familiar with the varieties of Catalan pronunciations, including Valencian varieties of Catalan and the North Catalan pronunciations of Rosselló/Roussillon. I'd be interested to see if some bits of vocabulary might be opaque to Catalan speakers, for example "m'empachan" (they prevent me) or the archaic "mia".
Gascon reminds me of Castillian because of the basque influence,Medieval Occitan has more prestige than Medieval Castillian but only it's descendant,Catalan remained prestigious compared to it's sister idioms Valencian,Gascon,Limousin,Languedoc and Provençal.
Another version of Se Canta-Aquieras Montanhashttp://www.youtube.com/watch?v=qYMEirfg8N4