These photos were shot within a fraction of a second, this birds can do that with their throat feathers.
Hummingbirds have many skeletal and flight muscle adaptations which allow great agility in flight. Muscles make up 25–30% of their body weight, and they have long, blade-like wings that, unlike the wings of other birds, connect to the body only from the shoulder joint. This adaptation allows the wing to rotate almost 180°, enabling the bird to fly not only forward but backward, and to hover in mid-air, flight capabilities that are similar to insects and unique among birds.
A hummingbird’s ability to hover is due to its small mass, high wingbeat frequency and relatively large margin of mass-specific power available for flight. Hummingbirds achieve ability to support their weight and hover from wing beats creating lift on the downstroke of a wing flap and also on the upstroke in a ratio of 75%:25%, respectively, similarly to an insect. Hummingbirds and insects gain lift during hovering partially through inversion of their cambered wings during an upstroke. During hovering, hummingbird wings beat up to 80 times per second.
Based on my own observations, I’ve seen them chase each other at high speed and then brake in the air down to zero. On one occasion I was shooting pictures of one of them, it saw me and flew rapidly toward me, it stopped right in front of the camera then turned back to the nectar feeder. I thought it was going to crash into me.