Quickly pinch the ripe seed pod between your thumb and index finger and don't let go until your hand is in a container to catch the seeds. I find this works pretty good.

Thanks so much for the help. I now have about 20 seeds in the 1 qt plastic bag. They are all very green, but they did "pop" so I presume they are ready to be distributed!

...and if they don't "squirm" between your fingers, let go because they aren't ready to pop

You can also try wrapping a little bit of pantyhose round the larger pods and securing with a pin or those tiny wooden pegs you get from craft stores - thenn when they "ping" open hopefully some will be caught.

In reference to your green seeds comment: if you squeeze a fat but very green pod it will usually pop. What you want to do is look for the pods that are fading and getting a bit yellowy. If you catch them in the light you can see the seeds starting to turn brown inside. You will probably have better luck germinating these more mature seeds - but try experimenting!