Yes you can rinse it in h2o2 bath like in the Jorge Cervantes video, it's not BS. But that should be used as a last resort, if you can fix the conditions that are causing the powdery mildew it should, for the most part, clear up on its own. If there's not enough time then yes, you can submerse them in the h2o2 solution and the PM will float to the surface. Because THC is hydrophobic it won't dissolve in the water, you may lose a few trichs as they are brushed off, but it's better than smoking mold. Just make sure they dry thoroughly after rinsing them or they can easily get mold/mildew again.