He might have just meant spraying expandable foam or some other sort of insulation/stop-gap in some places where drafts blow in from the outside. It affects your cooling/heating efficiency.

Call the local building dept. they'll direct you to staff on call so you will get the right answer.
It could be anything from accoustical caulk at the vapour barrier to foam in the electrical runs etc. dependent on the local codes and requirements.
Here is a bsmt firestop detail that he may be refering to as "draft stopping" as well...
Basement firestopping detail on AE forum