i am also wondering the same thing.......any info would be greatly appreciated

The pods are about 1/4 of an inch and look like an elongated footballs. The pods grow after the blooms are gone completely (seeds are no where on the blossoms). There will be lots of pods on the stems. It takes a really long time for the pods to turn from green to brown. I don't get ripe pods until late fall and usually (in zone 5) after the first frost. Inside the pod are tiny hairs, those are the seeds. I wait until the pods are cracking, then put them in a baggie and shake the heck out of them to clean. You can just crush up the pods and sow chaff and all too.

Here is a pic of the seeds (zoomed)....

Scroll down where it says 'Images', then click on Seeds (Buddleja davidii):

Here is a link that might be useful: Buddleja davidii seed pic...