What is a tone chamber anyway? Do I need an accordion with a tone chamber?

Accordionland120 (a great free bass performance youTube channel) has this interested video comparison of accordions.

 https://www.youtube.com/watch?v=bXfBLUt08lM&list=PLqKEdI9h4tj0-Et84KoWg9_ntj6BlUipK&index=2