And now bouree on a diatonic accordeon and vielle (a roux) my favourite combination.
The accordeon in the OP's link was a CBA... with a modified stradella bass system. The first and fifth rows on the treble side are duplicates.
4 patterns gives you all 12 keys.
Here is Marc Perrone a few years back...note the small accordeon hanging from the mic boom. It is a Castagnari.. I believe the model is MIGNON.
He is now wheel chair bound, I believe MS... but continues to play.
In this second link Marc plays his compostion "La Valse a Joseph". Though there is no video, there is an excellent montage of photographs well worth viewing. One of thje photos is of Marc playing his custom 4 row Castagnari. This is a four row diatonic, not a continental chromatic. Note the bass buttons. The piece of music and his playing are extraordinaire !