Buddhism  explains why sorrows exist in the world, and explains in reasonable, cogent, realistic ways (beyond some rather more doubtful and fanciful explanations it also offers),  provides a vision which offers peace and compassion amid, and transcendence of, all human suffering, and, simultaneously  offers a workable path toward the alleviation of such suffering and ugliness in this world in ways vitally necessary for our species' future.
If Buddhism failed in those three hard tasks, I don't think it would have much value. Fortunately, I believe, it does not fail in those tasks. Thus, I can say that this talk is as positive and optimistic in tone as it is sad and broken hearted. It is not merely one or the other.