Thats because the ice water makes the oils harden and become brittle. Thats why you use room temp water to wash them.
Im after the cleanest product I can get. Thats why I have a carbon filter feeding into my tent. Another filter feeding from tent air to the fan and some mesh on the back of the fan.
Each filter collects quite a bit on it over the 24 week cycle but there is nothing you can do about the dust that is kicked up from the grow medium if your using soil or perlite. My washing is no where near as rough as the video. Could even go as far as saying its a lot more gentle then had the plant been out doors and gotten rained on which is how they naturally get washed.
But each to there own.
This is exactly the same as the on going debate about watering curing. Youll have both on either side set in there way so your better off trying things out yourself with a small quantity to see if you like it.
I myself am a fan of it. but I also enjoy the taste so I only water cure 1/4 of what a harvest and save that stuff for when im out in public since it has no smell or taste. You can smoke it right next to some one and they will believe you when you say its herbal tobacco.
Here is the end result im getting after being washed and dried.
http://postimg.org/image/eh5fnxvn5/