Looks good, although there is definitely a "pumping" appearance - not all of the time, but probably 85%. You lean forward then rock back... I don't think it would be so noticeable if you tried to keep in mind that your shoulders should remain over your hips. You seem to be leaning over the pommel, then rocking back... as has been said, try to loosen your hips. Maybe imagine a rolling motion from your waist down?
Overall, you look great! Especially since you are riding with too-short stirrups - it always makes me feel awkward and stiff when my stirrups are too short, lol.