In the marketing and selling of homes, there are a number of active tasks that the Broker undertakes: calling prospective Buyers, Broker previews, Open Houses, canvasing neighborhoods with for sale flyers, emailing/calling one's sphere of influence informing them of the available property. The principle here is to go out and get Buyers.
There is also passive marketing: entering properties into the MLS database, PPC campaigns, etc. The principle here is to let Buyers find me.
For Sellers to get the most bang for the commission buck, Brokers augment active and passive marketing.
Regarding domain brokerage in general:
What degree do Brokers actively market domain names? Do Brokers have contacts in other industries that they contact weekly, providing them a list of domains covered under Exclusive Agreement? If so, exactly which companies in which industries are contacted? Do domain brokers work WHOIS records for prospective end-users and send auction invites or notify them that domains are available that may fit their business?
This information should be disclosed to the Seller when a non-circumvent clause is on the table. Exactly who can't the Seller sell to within a certain time period?