There used to be in Late Middle French and Classical French a (mainly spoken) contraction of the enclitic -vous with its host verb, essentially replacing the 2nd person plural suffix /e/ par /u/:
Avez-vous > Avous
Savez-vous > Savous
Allez-vous > Allous
For example, this citation from a letter of Marguerite de Navarre, sister to the French King Francis the first (1492-1549):
Mais qu’avous fait voyant ma repentance ? Tost avez mis fin à ma pénitence !
(But what did you do upon seeing my repentance? Soon you put an end to my penance!)
This had disappeared in French (but I’ve found more modern mentions for other Oil languages) by the time of the standardization of the language, except as a colloquial or regional variant, and those in turn disappeared once subject-verb inversion stopped being used in the spoken language.
However, I’ve found some mentions of the persistence of this usage in 20th Century Canadian French in the "Glossaire du Parler Français au Canada", which sadly doesn’t go much further on the vivacity of this usage, or its geographic spread in the Americas.
"Av’ous vu mon petit garcon?" (p. 82)
"Sa’vous où il est?" (p. 614)
The clip from the question is most likely an example of this usage, but with the information at my disposal, I can’t determine whether it’s still alive within the idiolect of the singer or an archaism passed along a traditional song.