The hover control in that short clip looks very good! Are you going to be fitting the leading edge root extensions? These generate quite a lot of extra lift, and IMO the slower you can get the model before losing aerodynamic lift the better. Also, on the later Harrier variants, there are some strakes fitted to the lower fuselage between the nozzles when the gun pods are not fitted. They are shown in the photo:



These really make a huge difference in hover stability - pilots found that hovering with the guns was more stable than without, so they designed and fitted these when guns were not fitted. It has something to do with reducing the vortices and eddies created right under the fuselage as the jet blast from the nozzles on each side mixed. It might be worth putting something similar on your model. The other point to note is that the airbrake is extended with the nozzles down - also has a stabilising effect for similar aerodynamic and fluid dynamics reasons, but they are beyond me!