Best of all is Dr. Lucie Green from University College in London, who describes the unsettled state of the science [at 3:35]:

„It is a very very complex area because the sun’s activity controls how much visible light the sun gives out, but also how much ultraviolet light and x-rays that the sun emits and they create a web of changes up in the earth’s atmosphere producing effects that actually we don’t fully understand.“ (..)

The weak link is solar physicist Mike Lockwood who makes irrational and unsupported claims about solar activity only affecting regional climate and not having a global effect.