Hmm, reproductive stress may be the culprit. However, another potential cause is the pollen is toxic and it is not making its rounds with the birds and the bees. The amount which would normally be consumed by other species could be lingering if there is reason to leave it alone. Just a thought.
Cool video. Makes me sad for the tree though. Maybe not the case here - but often when a tree puts that much energy into reproductive structures, it is becase it is distressed. Methinks the tree is dying.