"I don't know about you, but when I heard the speaker in the video say that cosmic rays affect the amount of global cloud cover, I felt like hitting him over the head with a wiffle bat."

My reaction was to be rather skeptical, but if it's actually true that cosmic rays affect about 2% of cloud cover, then it's indicates that more study is likely to get further results towards getting greater understanding. How is it known it is 2%? Is this the most it could be, average, least?
This is very new idea- more brains, more work needs to be done before I can form a more definite opinion about it.

If cosmic rays are having that much of affect on water molecules, what other affects on other compounds/elements is occurring? I'm not sure I understand the mechanism, does this have to do with small supersonic shock waves? Something to do with magnetic fields? In other words it seems there is a lot to know about this and other things related to it might more important than how it affect climate.
Does it add to existing clouds, does it lessen existing cloud, does it matter what kind of high energy particle is involved. Etc.