Can someone give a go at explaining it more simply since I have failed twice now?
The AGS funds contain about 10% of the total PTS in existence. When BitShares DNS is launched, these PTS (just like all PTS) will generate some shares in BitShares DNS (about 5% of the total DNS supply). These DNS-shares will still belong to AGS, which means their purpose is to fund DAC development. Clear so far? Short version: AGS will control a large number of DNS-shares.
If you help develop BitShares DNS, your name (or whatever identifying information you like) will go in toast's magic spreadsheet, and when BitShares DNS launches, you will be rewarded a portion of the DNS shares that are controlled by AGS.
TL;DR: if you help develop BitSharesDNS, you will be paid in DNS-shares.