You too? They really degenerate while flowering/seeding don't they? I thought I was doing something wrong.
Well, as for collecting the seeds...it's pretty easy. Similar to a capensis or spatulata, I hold a pure white piece of paper (folded a few times for rigidity), and tap the seed-stalk against it. If there are any ripe seeds, they fall off really easily onto the paper. Note of caution: The seeds are itty-bitty-teeny-weeny. If they fall off the (pure white) paper, you'll never find them.
I only just sowed a few (a couple of days ago), so I can't tell you how long they take to germinate yet.
The D. burmannii in my collection that are treated to an occasional protein supplement on legs (or wings) live much longer than the plants that subsist on a vegetarian diet. I've kept some plants from Beerwah for well over a year, while freely flowering, without any signs of diminished growth. They probably are still producing seed for their new owners.
Seedlings that are fed also exhibit improved growth, in my experience.