100% Powdery mildew. Battled it a lot over here. In my experience, the only way to actually prevent it from spreading once you see it is using a sulphur burner. If its caught super early you could remove any infected foliage and burn sulphur once every 3-4 days to prevent it from spreading.
But in your case being in flower and it's already everywhere.. If it were me, I'd chop down and start over. It looks like it's running rampant in there.
Excellent air circulation and ventilation is important for preventing it too, but once it's in there and taken hold, no amount of wind and fresh air will stop it.
Sorry bro..
[EDIT] I looked at the video again... They are in pretty early flower and probably could be saved if you have the means to setup a burner.
I would first wash them all very thoroughly with wettable powdered sulphur in a spray bottle. Then set up a burner to come on for 4 hrs per night for a week, then once every 4 days up to week 6. With the PM already in the plant, as soon as you stop with the sulphur burns it will start to regrow, so time when you stop about 10 days before you plan to chop. The sulphur will volatilize and will not affect the buds.