Those are rhetorical flourishes to keep people's attention and develop his ideas. He's the only president in living memory who's really held the room's attention, because literally no one knows where the ride is going when he starts. He's a very good public speaker in the classic sense. When he hammers a point home, he does it three times. Fits the old rule of, "Say what you mean, say it, then say it again." When he changes direction he also takes us on that journey with him in steps, like the example you give above.