Fast fingers

Here's a Portuguese piece I found on You Tube. This fellow - his name is Nelson Costa - is a very fast player. The sound has kind of a carnival feel about it, and that has to do with the tuning of his box. Many of the Portuguese players favour what they call wet tuning or full musette. I found a good explanation of this on Wiki:
The tuning used in accordions, also called "wet" tuning, where two or more sets of reeds are tuned slightly off pitch from each other, giving a vibrato effect. True musette tuning uses three reeds, one "on pitch", one slightly below, and one slightly above; however, many accordions only use two sets of reeds tuned slightly apart from one other. The degree of "wetness" is determined by how far apart the reeds are tuned. Musette can also mean a register setting of two middle reeds together (two "clarinet" reeds equaling a "violin" reed) plus a higher octave reed, producing a pleasant, bright sound that is associated with French accordion music.

The box i play is tuned with some musette, particularly on the right side, but not nearly to the degree of the instrument in this video. It's possible to change the tuning of your reeds, but it requires either expertise or money - as somebody who knows what they are doing has to scrape and file the reeds to get the sound just so.