Your pavers are porous. When sealer is applied to your driveway for instance, the pavers absorb it. Two reasons cause that white cloudy film on your pavers:
Number one is moisture. If after pressure cleaning, the job is not given time enough to dry completely, the sealer then traps moisture inside the paver itself. When that moisture tries to escape it is blocked by the barrier set up by the sealer and causes that white look you notice. It is possible to improve the look of your pavers if this happens, but the results do vary.
Number two is saturation. Since the pavers are porous as previously explained, if too much sealer is applied, the paver becomes saturated with the product and becomes not only white, but also very slippery and dangerous. Improving the look of your pavers if this happens is very difficult and costly and is not guaranteed either. A good alternative would be Color Sealing (staining).