Mr Neutron lad,
That part is clear as mud. So here goes; Once the air dried buds are dry on the outside, stem cra... and all THEN cut nugs from stem and jar them.
Now the outer part of the bud is dry but the inner part of the bud has moisture remaining. This moisture will spread to the outside until the entire moisture content is spread throughout the bud more or less evenly.
When you burp the jar you are letting out moisture laden air and replacing it with air that is a bit more dry. When you seal the jar (with the dry air in it) the dry air will pull moisture from the bud. So each time you burp the jar you are drying the contents in small increments.